There's a lot of negative comparisons of fallout 4 to the previous fallouts. A bunch of the complaints are quite valid for vanilla fallout.
But, how does fallout 4 fair, today, modded as much as possible?
Quite a few of the annoying issues can be fixed by mods, at least they were for me. So I actually think it does ok, today. of course it's not a good thing that it needed these mods, but once they're in, it beats fallout 3 for me, pretty easily. Although I really like the settlement system in Modded Fallout 4, so that's a bias for me.

I have roughly 200 mods and about 170 of them are fixing issues and tweaking things to make them more balanced. That's hard to give it a good rating when it requires so much to be moderately enjoyable. Fully modded, I'd say maybe a 6/10. Without mods, I'd give it a 3-4/10. The only real reason I still play the game is because of the settlement system. There just isn't much else to do in it after you beat it once. There's no alternative ways to play it other than choosing a different faction. Pretty much all the quests are still streamlined so you're pretty much doing the same exact things as before aside from the later half of the main quests. Settlement building, while a good addition, is still limited to all hell. It needs mods or it's just too bland to even bother with. That being said, it still requires quite a few mods to be good. Roughly 15-20 mods I have are strictly for settlement building to add more options.

Without settlement building, I'd give the modded game a 4/10. The simple lack of options for a second playthrough really hurt how much you can enjoy the game.

I like Fallout 4 quite a lot on its own merits, its not my favourite fallout in any way, that's still Fallout 2 but I like it

As far as how well a heavily modded F4 fairs in comparison to its modded predecessors. I think its easy to say that visually it blows the previous games out of the water in both its default state and especially when modded, the very best FNV has to offer can't come close to F4 in that regard. There's also the animation and weapon mod scene that made up my bread and butter in modding, which is by far the best of any Beth game, no contest. Then there's Sim Settlements, a mod that along with its community made addons is one of if not the most impressive and game changing mods ever made for a Fallout game.

But in a lot of ways, ways that I consider more important then the last few, are considerably worse. For instance the quest mod scene in F4 is dire, I can name 4 good ones off the top of my head and 3 of em come from the same mod author, FNV has dozens. Pretty easy to see why that's the case with the whole voiced protagonist problem among other things.  

In short I think modded F4 is better in a ton of ways that don't matter much but is worse in ways that do matter, at least when it comes to my preferences and to the longevity of the game. If I had to assign an arbitrary score to it I'd say 5/10, its fine for what it is but its no modded FNV.

Cheers

I feel like most rate NV way up at the top, and then all the others near the bottom.
I'm completely satisfied with Fallout 4 once it's modded. That doesn't mean I think I think it's legendary. Just... I'm satisfied. That means one long playthrough, but not necessarily two or three times. (It's very, very rare that I play rpgs more than once, those are basically legends if a second play-through is more important than starting up a new game.)

For me it's way, way above fallout 3, there's almost no contest on any level for me. I didn't really care for F3, though, so I'm biased. I may have been soured by Bethesda's choice to not pick up the story where Black Isle had left off (Obsidian took up that gauntlet.)

It beats even Fallout 1 and 2 on several places. Sacrilege, but it's true,for me. There are four factions in F4, and ... no competing playable main factions in the early games. Lots of small, local, relevant choices, yes, sure, they excelled there. But they don't have the NCR vs Legion vs House, or f4's factions,all struggling for control of the "world" and all playable. The faction choices were typically made locally on a large number of small levels. Nice, but NV and F4 innovated on being able to actually join the bad guys (or the grey-area guys,) and that's perfect for Fallout.

So for me, if NV is the 10/10 of Fallout games, then F4, modded, is an 7 or 8, and F3 is a 5 or 6, the original fallouts ... they're hard to rate against the modern 3d games, but if I think about how I felt playing them at the time I'd put them at a 9. Unmodded, I am not interested in F4, and it gets a shrug out of 10.
I've probably got dozens of hours just slowly walking around the commonwealth with my jaw hanging open, just... looking. I can't say that about any of the previous games, no matter how much I liked them. Ok, maybe visually, New Vegas Restored with the Sierra Madre inexplicably on the strip. Visually, it was stunning like nothing I'd ever seen before. But not dozens of hours worth of stunning.

My last playthrough I had 379 total esp/esl plugins...it was so much "anti lore" but that's what made it fun...having the freedom to basically create a "living virtual toybox" with whatever whereever has been what has kept me with the game since it's release when everything else has come and gone in a measure of days/weeks this has lasted for years

I started the series with NV and it is great in so many ways when highly modded, then FO3, then FO4. Maybe I'm a lousy judge, but I raise an eyebrow when I hear FO4 being dragged in the dirt by comparison to the others. I never had a chance to play any but these three.

I've cut my modding teeth on these three games. Love RPG and FPS, so these all fit my preference. Hitman makes an excellent point about the almost utter lack of quest mods for FO4, but visually it's the one I like the best. The latest PC build was specifically designed to handle the heavy visual and immersion mods I enjoy in FO4 (and SSE). I seem to find new directions/places/people/options even after hundred's of hours and several runs. I also run several profiles usually, which breaks up a stale play thru.

So although I may be a bad judge and really more of a user than a mod creator, I rate a heavily modded FO4 very high. 8/10 for me anyway,

With my fully modded FO4 load order I played with for a little bit before things broke and I gave up,I had decent fun. Granted,I was structuring my load order to emphasize the action as opposed to the rpg elements of the base game. It basically became a STALKER 1.5/Metro Exodus prototype in terms of how it played. Just roaming around in a huge nuclear wasteland sandbox capping raiders,trying not to breath the radioactive snow,and just overall getting into firefights. Just with that,I'd give it a solid pass in fun factor. Keep in mind that I am just talking about Fallout 4 fully modded on it's own merit and not in comparison to previous games which I think it still falls far behind. Probably would've enjoyed it more if there weren't games that come out of the box doing pretty much the same thing but better. Overall,6/10.

It is not quite there yet for me.

It still lacks mods that improves immersion like FNV's Project Solid and Enhanced Camera but it has a lot of impressive mods such as the various new weapons/armor added by the modding community, quest mods and recreations from other games that looks so good with the updated engine so it is a 6/10.

Yeah I almost forgot about those two, although I found NV pretty awesome even before those came along.  One thing I can't forgive F4 is the removal of simple sheathed weapons.  The F4 mods on the subject are awkward compared to the simplicity of it in NV.  I doubt we'll ever see a simple plug-and-play F4 mod that simply gives us NV-style sheathed weapons.

Games from the Bethesda Game Studio are always dependent on their modding community. I think vanilla Fallout 4 didn't bring as much to the table as we all hoped, but thanks once to mods you can customize your game to your liking. You can make Fallout 4 a stunning game, if you have the pc rig for it.

I have a lot more fun with my modded play throughs than with the vanilla game, but that applies also to other games from tjhe Bethesda studio. I would rate games with mods always higher than vanilla, pure for the fact I can make the game to my liking.

In New Vegas, if I wanted the main story modded, it would be to flesh out the legion, perhaps -- or dlc-ish expanions to show us the NCR capitol at its best, and legion territory at its "best."

But one thing that, for me, really stands out with wanting a plot mod in F4 -- (possible spoilers)
On my first meeting with the institute, I really had only one question, and I wanted it answered immediately. "Are you seeing the synths as tools rather than people, because they can't feel pain and are only entirely simulated, fake consciousness, etc, or simply because you created them and believe that this alone grants you rights over them?" That was it. That question. Asked and answered immediately. I mean, are the synths just programmed to act sentient, or are they basically living,thinking, feeling clones -- people -- with a couple of synthetic parts? I wanted to know, immediately.
The answer would then entirely dictate, right there and then, as to whether or not my "good" character purged the institute, or sided with the brotherhood or railroad. It's that important. Compared to that, all the other stuff I was allowed to ask felt like meaningless small talk -- compared to the urgency of whether or not I should simply be opening fire.
I think that's more a bigger issue and important to me than any plot enhancements I'd suggested for NV.

I bet it could be solved with mods, though, so there's hope. I've been tempted to add it in myself.

I might play Fallout 4 again once F4 Miami or F4 New Vegas is released, otherwise not so much. Even with mods Fallout 4 just is not for me.

Mods can never fix most of F4's problems. With F3 and NV, there were always mods that could fix most of the problems. Not with F4, unless you were to rework the entire game.

The quality of Fallout 4 mods especially armour and weapon mods is vastly above previous Fallout games. Many weapon mods are vastly better than the vanilla weapons whereas in previous Fallout games I feel this is not necessarily true.
However the one area I feel Fallout 4 modding is lacking is quest mods, Fallout New Vegas had plenty of amazing quest mods which helped keep my interest for hours upon hours but this is not the same with Fallout 4 which is a game that I find hard to get myself to play due to how repetitive it can get.

Fallout 4 with mods is on par with new vegas and fallout 3 with mods. The modding community just does so well on these games to expand the content of the game. Some people are kinda bias cuz yeh base fallout 4 is butt, however with mods though it fixes the game and enhances it.

I'll eventually get back to fallout 4. I'm waiting for bigger things to come out for it. There is definitely big mods out for it already, but I want it to settle even more to have like the perfect modded fallout 4.

It depends on how much you require voice acting -- if you won't play a quest or new land unless it's voice acted (both player and npc), the number is limited. Under New lands, new locations, and quests, those categories have a fair number now, otherwise. I haven't even begun to try them all, not even all the top rated ones yet. Maybe I'll end up disappointed with the ones I haven't tried yet.