I have a couple.
I really like the 9x23 Winchester. It enables me to have 357 Magnum ballistics in a 8+1 capacity autoloader, with less recoil and less muzzle blast. You also get faster reloads.
Second will be the 460 Rowland. Same as above but with 44 Magnum ballistics vs the 357 of the 9x23.
Third would have to be the 10mm, that gives 41 Magnum ballistics in an autoloader.
JMHO, YMMV.