Going from when I first started carrying to the present:
Glock 21 - Too big.
Kimber 1911 (Custom II) - Would not function properly. This was followed by a Springfield GI 1911 (enjoyed the gun, but didn't think sights or finish lent to carry). Tried another Kimber (TLR II), same set of problems.
Glock 19 - Liked it, but didn't enjoy shooting it due to the grip angle. I'm thinking about revisiting this in the near future.
Kahr PM9 - Pocket carried for almost a year, had no problems with the gun until one night when I struck a cat with the car and did the merciful thing. The Kahr fired the round in the chamber, then failed to go into battery with the next round. Chose to try something else after that.
Beretta 92/92 Vertec - Not my favorite handgun in the world, but it's what the army uses so I figured I might as well become proficient with one. This included carrying during the winter months when jackets are no problem.
HK P2000 - Similar to the Glock 19 in size, but I liked the ergonomics. This has been my primary CCW now for about 4 years. Holsters are IWB, OWB, and shoulder which makes it carryable in most forms of dress. Thinking about going back to the Glock 19 because I'd like to do all my own end user maintenance, ease of access to parts, etc. Even if I give that a shot, the P2000 isn't going anywhere. It's been 100% for about 10k rounds.
S&W 340SC - When it's scorching hot outside, formal dress, or other occasions that prohibit carrying something larger, the .357 J-Frame easily carries on pocket or ankle. Basically, it's the gun to carry when you can't carry a gun. Also makes a good BUG.