7mm Rem. Mag. and 180 grain .300 H&H are my favorites for 'bou. Anything that is a real flat shooter (a lot of times you will be taking shots well over a 100 yards) is optimal.
Up here our shots are very long because of the lack of cover. I shoot a 270 and a 308 and I like a 130 grain as it shoots flat and does less meat dammage on the way out.