Over the years I've accumulated a wide variety of .22's and would find it pretty difficult to pick a favorite. That said, two of my favorites are a pre-war Mauser es340b that was made in 1936 and a Springfield Armory 1922MII military trainer made in 1937. I bought these rifles as a package and the machining on these things is phenomenal. I'm certain they would cost a fortune to manufacture today.
I've more recently been enamored with lever-action rifles for some reason. I like them all...the Marlin 39's in all flavors, the Winchester 9422's, and the Henry's. I still haven't run across the "right" Browning, but when I do I'll add that to the list.