I would like to have a Ruger SP101-22, but Ruger seems to be really behind on their orders. Other than that and maybe picking up a nice S&W model 36 sometime i am quite happy with the handguns that i have now.
Automatic: I can drive nails with my Gold Cup. No sense looking further.
Revolver: My S&W 629 .44 Mag with the full-lugged 8 3/8 barrel would also be ideal. Straight-shooting monster with less kick than a .38 snubby.