Uh-oh - can o' worms...
You don't need to carry a sidearm.  If you do, none of the conventional semi-autos are suitable.  If you absolutely have to carry a common conventional semi-auto, full house 10mm heavy bullet loads would be less bad than the other choices.
In Alaska I carried extremely heavy 45 Colt loads for many years and heavy bullet 44 mag loads for a few years.  I encountered MANY bears at rock-throwning distance, some at face-to-face range.  I never had to shoot a bear under those circumstances.  Again, you don't need to pack heat for bears.  (OK - I would carry, but bears are *almost* an insignificant reason for me to carry a firearm).
A short barreled 12 ga pump with a proper sling, a Marlin Guide Gun, a bolt-action rifle in 308 or larger caliber, even a 30-30 with good bullets would be "better".  If you carry a pistol instead, stick to large calibers with heavy bullets.  44 mag, heavy 45 Colt loads, 454, 480, etc.
HTH <bracing for onslaught of posts>,
Tom