I have been debating over the 980TI or the 980.
I played FNV and F3 for years, and I have moved on to Skyrim. I have learned alot with regards to manual installation, esp/esm edits and the importance of backup and load orders all from FNV/FO3.
I predominantly play Skyrim now and I am anxious to play FO4.
However I am waiting on a couple of things:
1. The Geck - Which is said to be coming out next year
2. F4SE - Which was just released recently
3. Patches & DLC from Bethesda - Yes it may be a long wait, but I have learned this the hard way and when your things hit the fan because that one mod you forgot you installed 3 years ago is not incompatible with the latest patch you're gonna have a bad time.
Back to the GPU, the golden rule has always been to get the best you can afford.
Having said that I know Skyrim has problems with cards over 4GB of VRAM, I don't know if the same will apply to FO4. I assume not, so that would dictate I should get the 980TI.
Now since I am waiting for patches and the creme da le creame of mods to come out I am gonna wait till we know more about FO4 with regards to the specifics like the engine, any need for memory block allocations etc.
I have actually been trying to avoid the FO4 forums and posts to avoid spoilers. But if anyone can provide any spoiler-free info on the mechanics of the game please do!