I'm pretty sold on, at minimum, .38spl. I used to shoot my uncle's old NYPD issue S&W .38 (4 or 6 inch?) as a teenager at it was easy then. He also had a S&W .38 stubbie back then that we used to shoot as well.
I may consider a .357 mag becuase it can shoot .38spl +p ammo and, if I wanted to try it, I could shoot .357mag ammo as well. I have hands that are on the smallish side so I might not enjoy it too much. I won't know until I try a rental or 2, but I'm sure 99% of my shooting will be with .38spl and +p ammo.