Really can't go wrong with a wheel gun in any caliber you like.
Here's what I got when I hit the "what next" point.
Shim the trigger and hammer, maybe a light stoning on the trigger return body and a lighter return spring... End up with a double action revolver that's as easy to shoot as most semi autos, and no magazines to fumble with and cost you $$$.
You can go for an obscene caliber if you like, but you will likely end up not shooting it much. 357 magnum chambering gives you a lot of options, especially in a full sized steel frame gun.
Here's what I got when I hit the "what next" point.
Shim the trigger and hammer, maybe a light stoning on the trigger return body and a lighter return spring... End up with a double action revolver that's as easy to shoot as most semi autos, and no magazines to fumble with and cost you $$$.
You can go for an obscene caliber if you like, but you will likely end up not shooting it much. 357 magnum chambering gives you a lot of options, especially in a full sized steel frame gun.