Nvidia GTX 760 SLI
It supports SLI and Crossfire. Just the thing here is that the GTX 760 alone is enough to handle all that the game has in terms of visuals. You won’t see any enhancement with two cards, maybe somewhat more stable frames even.
GW2 is a processor bound game so say for example you’re running an AMD CPU with SLI 760, changing to an Intel i5 4690K for example would increase your FPS by at least 1/3 at the minimum.
I’m running the intel i7 4820k atm.