the r9 280x is better why?
more streamprocessors
more texture units
More memory (1Gb more)
in crossfire the r9 280x will destroy the gtx 760 :/
But the r9 280x will require more energy from the psu 600w recommended
the direct competence of the r9 280x is the gtx 770, so this was an unbalance vs
I hope it helped you if you have the money and the psu go for the r9 280x