My Model 18 .22. It was my first handgun, and it may very well be my last, a few decades down the way. (Seems to me, a lot of older guys end up reverting to .22 due to physical limitations.)
Besides, it was a gift from my parents. My dad bought the revolver for their second anniversary present to themselves. My parents gave it to me when I was a teenager.
Not to mention, it's a tack-driver.