the r9 280x is better why?
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