770 because of what everyone else said.
Additionally, I like some of the 'extras' that an nVidia card brings to the table in general. You've got fun little things like Physx - sure not huge but it's a nice addition in borderlands. And you've also got things like the nVidia Shield, which might not be in the future, but the option is there! Tack on the solid 770 performance and strong driver support and you've got a package that's hard to beat.
One thing to mention, I'd recommend the 4gb version of it. Some people may think I'm crazy, saying reviews don't show performance differences between 2gb and 4gb, problem is those reviews aren't testing correctly. Another myth is that 'once a game uses that much memory, the card won't have enough power to even run a usable framerate.' Texture size and framerate performance are independent unless you just don't have the vram to support it. A first hand example of this is a modded skyrim. On my 770 4gb (in my other rig) I use about 3.4gb. On my 780gtx it uses 2.8gb, same Skyrim install (This is why you can't compare btw.. the system will scale to what you have. So you can't say "Well on my 2gb card it only uses 1.7GB so that's all it will use on a 4GB card!") Anyway, moving on, my old gtx 295 would use all it's 768MB of vram (same modded skyrim) - the card had the power but the VRAM was trying to work so hard it caused massive stutters. I'd run a clean 60fps standing still or even in a fight scene, but once a new texture needed to be loaded, it would stutter until the texture was loaded up. I also EVERY once in awhile can get a stutter with the 780 that the 4GB 770 doesn't have (I have to almost try to make it happen though.) Also worth noting, I have zero FPS changes going from super high res textures on a 780 to low res. The texture fills happen over the VRAM - outside of any processing that's actually happening. The GPU itself could care less how large the textures are (file-size wise) - it's the memory that's going to have the biggest direct impact on that (which to be perfectly honest, in most games is no difference at all.) It's when you have MORE textures that the GPU cares, not what each individual texture size IS. I hope that makes sense! This also explains why almost all reviews out there show no difference between 2GB and 4GB VRAM. The testbed is not accurate. And, admittedly, we haven't hit that era yet in gaming where it's even possible to easily simulate the right environment. But that might be changing VERY soon!!!
Anyway, I say all that to say this, these NEW games coming out are a question mark as far as how much VRAM they'll use. John Carmack did make mention at QuakeCon at one point that he's looking forward to the extra memory of next gen consoles so he doesn't have to bother with compressing all his textures. It'll be interesting to see if that overflows to us in the PC world. What will it mean? It's going to mean that, those with 4gb "pointless" cards are now going to see some very real-world, tangible benefits! (that is, sexy sexy textures)
At only $50 difference between the 2GB 770 and 4GB 770, it's almost a no brainer.
