If by "pistol" you mean handgun; Smith & Wesson 686.
If by "pistol" you mean semi-auto handgun; none are really my favorites, they are just tools, but my Smith & Wesson M&P40 M2.0 4 INCH is my most versatile.
Right now it would either be my Shield Plus with the 15 round mag or my FN 509. The extended mag on the Shield really helps the snapiness on those smaller carry guns and the FN just fits me. I'm also a fan of the Smith and Wesson M&P 2.0 series.
One I don't currently have: Ruger GP100 in 357 mag with 4" barrel. I shot one when I was in Florida and was impressed with it. It shot 357 mag easily. I remember when I finished shooting, I told myself "I just found my next handgun purchase."