So I never heard of F3FNV till today. What's the advantages/disadvantages of both?

Well never heard of F3FNV but after a quick google search that pulled up nothing I'm going to say go with TTW, active community, still getting updates and it has a pretty good database of converted Fallout 3 mods that are converted to specifically work with TTW

Hope that helps but like I said, never heard of the 1st one

I've also pulled up a quick google search and it resulted in nothing, would you mind explaining or showing what you've heard/seen of F3FNV? Like Tribal Raven I'd say go with TTW, but a forewarning; my experience of modding TTW was a pain, it took forever and it didn't pay off. But that's just with my experience, most would probably say they've got it running without any major problems.

Here: https://www.gunetwork.org/t1151-f3fnv-v-2-2-0b-fallout-3-import-to-fallout-new-vegas