I like my Walther P22. It's a fun little range gun, but if you're considering something in this class, I actually recommend the Ruger SR22 instead. I love this gun and think it's superior to the Walther.
Neither of course. would replace my Ruger MKIIs though. If you don't mind the larger size, any variant of the Ruger MKII/III series would be a great choice.