All 3 will do the job quite easily but if it were me, i'd go with the 270 win and run 150gr or 160 gr Nosler Partitions. The 150gr NP's have worked incredibly well for me over the years and that is my round of choice, even for moose.
As for shooting grizzly, I don't know if i'd shoot out to 200 yards, it would depend on a couple of things before I made that decision.
