Which is the better choice

If someone asked about this already i apologies, i just could not find this specific topic. so my situation is, im looking to upgrade my GPU "currently a GTS 250" i have a budget of around $130 to $160 and the best cards i can seem to find are the gtx 650 ti boost and the R7 260x. i want something just to play modern title games smoothly at 1080p. i heard that the new AMD cards have some new features like mantle, and also there is the fact that the play station 4 and Xbox one use AMD so im wondering if that will mean most new titles will be optimized for AMD. but when i look up bench marks the 650 ti B seems to do better right now. i know the drivers on the new R7 are probably not that optimized so i would like to think performance should increase with driver updates. what do you guys think i should go with ?   

Alright, well you've asked a bunch of questions in there so I'll do my best to cover at least most of them.

Personally, I prefer nVidia graphics cards. This mainly comes down to my personal experience with both companies and I simply prefer nVidia graphics cards over AMD. So naturally I would recommend the GTX 650 Ti boost. That said, both of those cards could run almost every game at 1080p on high settings while maintaining an adequate framerate. You are right in saying that in general the 650 Ti boost does take the cake in almost all gaming scenarios.

As for drivers, I wouldn't expect much improvement out of the R series AMD graphics cards even though they were released more recently than the 6xx series nVidia cards. For one, the architecture itself is identical to that of the 7xxx series AMD cards (with some minor tweaks) and the last few updates to the AMD drivers haven't shown substantial improvement in performance for the new R series cards.

Mantle hasn't been released yet so no one really knows how much of a performance boost will be gained from the new interface, or even how many games will support it at all. So really, there is no point in me adding to the speculation around it. If you really want to know the answer to this, then you'll have to hold off on your upgrade for when Mantle is finally implemented in a game!

Will an increase in AMD optimised games hit the PC? I would say undoubtedly. How much of an increase? Probably not a whole lot, however the "next gen" consoles have only just been released and almost all of their launch titles are exclusive to each platform. There hasn't been a next wave of cross-platform releases so again we don't really know. That said, BF4 is a cross-platform release and is optimised for AMD GPUs. I find that pretty indicative. Optimisation can make a big difference in some games (Metro 2033 comes to mind), however in general the difference in framerate between using a graphics card that is "optimised" versus "non-optimised" is not all that substantial. The 650 Ti boost is the better performer, and is likely to run close to the R7 260x in most AMD optimised titles. (substantiated based on review gaming benchmark results) 

Personally if it were my dollars, I'd buy the 650 Ti Boost without hesitation. You're getting a beast of a card that falls in the current sweet spot price bracket that will outperform the 260x in nVidia optimised games and trade blows in AMD optimised titles. I also find G-Sync a far more appealing option over Mantle, and I would be setting myself up for a future upgrade of adding a second graphics card and buying a high-res G-Sync compatible monitor in a couple of years. Thats my 2c, but of course the choice is yours... Both of these cards would perform well and do what you need them to.