It kind of depends on the type of competition you might do.
Slow, precision, or fast action.
The ones you mentioned are well suited to the first type, like bullseye.
The 22/45, with the more upright grip angle seems, at least to me, better for steel challenge, action pistol and the like.
But you will have to try them.
As far as barrel length is concerned, that's never seemed to make as much difference as other aspects, like trigger action, the sight design, weight balance, mag release style, and so on.
Anything from 4.5 to 5" seems fine.
Lock the doors, they're coming in the windows.