I think the .50 AE Desert Eagle would probably be the best autoloader, but the problem with that is that it's huge and it's really much less practical than a big revolver.
The .50 AE Desert Eagle is 70 oz. The .454 Casull Raging Bull is 53 oz. The .460 S&W Model 460V is 62.5 oz.
Not that ftlbs is the best indicator of performance, but the .50 AE is about 1400 ftlbs, the .454 is about 1900 ftlbs, the .460 S&W is about 2500 ftlbs, and the .500 S&W is about 2900 ftlbs.
So the Desert Eagle would be fine, but the problem I see is that there are revolvers which are more powerful, more reliable, and easier to carry.
I really like the .460 S&W being able to shoot .454 and .45 LC, but I don't want to be the guy answering the "which autoloader" question by saying, "get a revolver."
This all leads me to say that the only way I could actually suggest an autoloader is if it was something much easier to carry than a Desert Eagle, in which case I think I'd have to suggest the Glock 20 which is 28 oz. and pretty easy to shoot for as light as it is.
Of course none of these are particularly ideal, but I really don't think people need to be condecending, either. If a bear decided to charge you, is a 12-gauge really going to do that much better? You can't carry around a rifle or shotgun on your hip very easily. Life is about tradeoffs. That's the reason some people don't wear their seatbelts. But before you go and condemn the people who prefer convenience to safety, ask yourself why you don't wear a motorcycle helmet when driving. Ask yourself why you haven't welded roll cages in all your cars. Because guess what! Even if you spent 50% of your life hiking around national parks, you're still more likely to die in a car accident on your way to the park. Just get the meanest gun you think is comfortable.