I carry several different pistols depending upon the situation and clothing.
Some of my repeat favorites are Colt Defender, Colt Lt.Wt. Commander, XD9SC, S&W 6906, and a few various 2" revolvers.

The thing is, while I would like to carry my CZ 75B Stainless full time for not other reason than that it has 19 rounds on board, it's heave and a bit too big for most situations.
So in the end, I have to confess that the two pistols I carry most often are a 642, specifically because it's light, and an LCP, also because it's light.
Neither of those pistols are optimum for a situation where a "belligerent defense" if called for, but their light weight means that I fulfil the cliche' that "it's better to carry anything than to carry nothing at all".

So yea, a 642 is usually what I bring along in a Don Hume J.I.T. holster pretty much anywhere.
These days with the terrorist **** going on, however, I'm thinking that I will start carrying the Lt.Wt. Commander more often. Still light, but not as featherweight as the 642, and I get to bring 8 onboard instead of just 5.