It really depends on your budget and preference.
Other gamers would like to go for high-end cards to play most of the new games on a stable 60FPS in ULTRA while others would rather have the game be playable in Medium to High with 40-50FPS.
For my opinion, spending more on a graphics card (only if you have a processor that won't bottleneck) is the important thing you need to have on upgrading your computer to play high-end games.
If you can get a GTX780 / 780 Ti, then go for it as it will last a long time before you upgrade to a new GPU. But if you're in a budget getting an R9 270X or GTX750 Ti is also a great option, it can run games in mostly high settings for the new games.