I've killed more with the 22lr than anything.
I'm not sure that makes it my favorite.

Really, the favorite changes from time to time.
Recently the 22 Hornet has been high on the list.
It's a dandy of a hunting cartridge.

I don't expect any time in the foreseeable future where I'll have or want to settle on a single rifle cartridge.
If I *had to* I hope I'd be able to be handloading for it. I'd probably have to choose 308 or 30-06

Thankfully right now I don't have to limit myself to just one.