I can't limit mine to one either...I like them all, but these 2 stand out above the rest:
First, my High-Standard Sentinel Deluxe .22
It belonged to my dad, and I have the original box and all of the original paperwork. I couldn't hit the broad side of a barn with it, but he could pop soda cans at 25 feet one handed all day long. I miss him.
Second would be my Star BM
It belonged to my brother, who, after showing it to me once, then cleaning it up and Duracoating it, gave it to me a couple of years ago at Christmas. He told me that it was his way of saying thank you for all I did for my parents while they were sick and everything I still do to help take care of our mom.
I've got several other handguns that I really like, but the stories behind these are what makes them so special to me.