It is 10-15% stronger, nvidia have better quality card than radeon IN GENERAL... and it can be overclocked better than 270x
GTX 760 best brand:
Noise:
MSI = 25dbA idle / 27dbA load
ASUS = 25dbA idle / 33dbA load
Gigabyte = 27dbA idle / 34dbA load
EVGA = 26dbA idle / 38 dbA load
Temps:
MSI = 29C idle / 69C load / 70C overclocked load
ASUS = 29C idle / 68C load / 74C overclocked load
Gigabyte = 36C idle / 68C load / 70C overclocked load
EVGA = 33C idle / 72C load / 76C overclocked load
Would go for MSI as the first choice then ASUS then Gigabyte/EVGA, but it's up to you (they are similar in performance)