I tend to agree with what Jack O'Connor said, that the .270 and .280 are equally as good. Use good similar b.c. 140 grain projectiles in either, the .270 marginally better sectional density, the .280 marginally bigger diameter. I don't think there is any significant difference. For slightly better performance than the .270 with slightly more recoil, I'd go for the .280 RCBS Improved or a .277 with a slightly bigger case.
