Another vote for Ruger Mark II/III, I have a red dot on my and use it for target shoot and dispatching ground hogs around the house, very accurate and very reliable.
Ruger makes a very good .22, so does Sig, walther and Browning. I am partial to Ruger Mark II myself, but that is just me. There are also revolvers available as well. My Ruger pistol is the target model, and I have had it threaded so that it can accept a silencer. The gun is a hoot. I think you will enjoy it immensely regardless of what brand you buy.
I agree the Ruger MkII si a nice .22 pistol, but lots of luck on breaking it down to clean after a range session. The release on the back strap and lining it back up after the clean is a major pain in the tush ! I finally dumped mine after a few years of it simply being too much trouble.
Get a Ruger revolver for ease and cheap plinking.
Of course, my .02.
And of course, no one is going to depend on a .22 for defense. Good cheap range time though !!
You can not go wrong with the Ruger 22/45. I have mine in stainless and bull barrell. I have put thousands of rounds through it and have yet to have a problem. I have never fired the sig misquito that I have, so i dont know about it. I have tried most of what is out there. I dont think that for plinking you can beat the ruger. the 22/45 frame is very similar to the colt 1911.