I'll answer your question...with a question: What's the biggest calibre that you can effectively fire without wetting your pants and/or bashing your shoulder into a punch-drunk flinch-induced oblivion, and still effectively smite what you want, at distances you hunt?
That's the one!
I've owned & liked some 7mm Mags, (smokeless) 45-70, 9.3x62mm, (& some bigger BP & smokeless toys in the 1/2 inch + category as well) and all did what I wanted without beating me into a blubbering whiny mess. I also very briefly owned one very light-weight .338 Win Mag with a narrow buttstock that taught me the limits of diminishing returns on pain suffered for energy, accuracy, and range gained.
These days the 9.3mm is the biggest (in diameter, at least) cartridge that I'll hunt with (other that in a lever-action of course, you 'need' something big in them), because so far it's proven itself capable of dropping deer & elk (and a dopey 'yote) on the spot from 30-370m with one shot as long as I do my part. I own a few bigger rifles, but not that impress me more.
It comes down to preference, tolerance, & tastes. And, the specific firearm and how it personally fits you overall. Hell, some guys actually like #####y fat chicks? More power to them, I say.