evga, msi, gigabyte, asus, in that order.
as far as the best.... the best at what? there are many factors considering the best. you might want the best overclocker, the quietest, the coolest, best warranty, etc.
the evga classified is by far the best 780 but only if you are considering the most exotic pcb platform the gpu is built on allowing for the highest possible overclocks combined with evga's legendary warranty. the next best would be the msi lightning. after that, their was the galaxy hall of fame, but they had catching fire issues and have since been pulled from shelves... never to return. asus does make the poseidon rog but ive honestly never seen them around.
if you comparing regular models, evga acx, msi twin frozr, gigabyte windforce, and the asus directcu2.... they are all very good cards that are roughly the same price and will overclock fine running the stock bios limited vcore voltage. not to knock the asus too much but, its has a voltage locked digi+ asp1212 voltage controller while the evga uses the unlocked reference ncp4206 and the msi and gigabyte use upgraded ncp4208 controller.