Depends on where I'm shooting.
Outdoors, by far it's 22 LR. The only 22 I've got these days is an old vfive screw, S&W, K-22 from 1948. It's got a lot of wear, but mechanically it's in great shape.
But, where I spend most of my shooting time now at indoor ranges, I don't really like shooting a 22. I prefer 38 Special, in one of several S&W, 38/357 revolvers. 10's, 15's, and 19's.
In a semi-auto it's 9mm.