Part of this depends what kind of shots you will be taking, particularly how far.
Let's assume you plan to shoot through 400 yards or so. I prefer the .30cals as I like having the benefit of the extra diameter on a tougher animal. Most .338 cartridges kick too much for my liking. The 7mms are good too you just give up some diameter and weight vs the 30.
Where I hunt, most of the locals use either a 270 or a 7mm.
If we're talking longer than 400m I'd lean strongly towards the 30 and 7mm magnums. But I've seen reports just this year of people taking them down with stuff as small as a .243.
Defining "Best" is a fools' errand.