Because you play mmo/moba and rpg games, you don't need a gtx 780, even for the next 2-3 years when you do decide to upgrade again. Mmo games are particularly cpu-bound, so graphics cards are not as important as the cpu. Dota 2 doesn't need anything fancy. Borderlands 2 doesn't need anything that fancy either.
I would get the gtx 770. If you are not going to be playing any graphically intensive games like Crysis 3, Metro, Skyrim, Battlefield 4, etc, I would actually save a little money and grab either the gtx 760, hd7950, or r9 280x.