If you don't reload and want a revolver with a good amount of power, but one that is also flexible to shoot different types of loads in with ammo that's easy to find, I'd seriously consider a .44 Magnum.

The 357 is good stuff, but it's not a .44 Mag. The 10mm is okay too, but in my opinion it won't do anything you can't already do with a .40 or .45.

I'm a .41 Mag guy myself, but I'll admit that the .44 Magnum might be the very best all around choice out there.