opinions are like butts... ( I'm being nice )
IMO, a couple things to look at here...
what type of gun do you shoot the best... if you are going to have a real self defense ( non hunting ) type of shoot at a bear, you are likely to only get time for 1 or 2 shots, so the gun you can get the fastest on target 2 shots off is best ( even if thats a 22 ) better to hit twice, than to blast in the air twice with your 500 Magnum...
now... to all these guys are posting, that saying they'd use thier Glock with these super hot 10mm loads... does the gun fire 110% reliable with those chosen loads ??? cast bullets ??? great if it does great... not so great, if you graze the bear on the 1st shot, & the case stovepipes... next, how much does this super duper slow down your 2nd shot ???
to the 44 mag revolver guys... can you get 2 shots are target very quickly... with those super duper hot loads ???
I own a Witness 10mm that I'd feel comfortable carrying, but I'd probably pick a more sane loading, my gun is not 110% reliable with super hot monster loads... I also have a large frame Dan Wesson 44 Mag snubbie with a barrel nut compensator... I know it works well with super duper loads ( I designed the gun for that use )... but it is an older blued gun, not stainless, like I like my rough & tumble outdoors guns... so I bought a Ruger Alaskan in 454 Casull last year... the gun is heavy, so that helps with a follow up shot, but it's still not as fast as my old Dan Wesson with a double tap on target shot...
if you are looking at more realistic loads for better auto reliability, or faster 2nd shot, avoid hollow points, & look at either FMJ round nose or flat points...
but thats just my opinion...