A number of respondents have used terms like fit and comfort and feel, these are among the most important criteria when choosing a protection handgun, these, along with things like conceal-ability, caliber, cost, and availability. What any one person thinks and says about a particular pistol, manufacturer caliber, etc. is only an opinion. They may share that opinion with others, there are more than likely those who differ in that opinion. My own opinion is based upon what I feel is important, the recommendations of others may affect how I choose candidates to consider. I try not to make an opinion on those things which I have not tried.
Nuff philosophy, now back to guns. Once caliber is determined, and size range, and $$ available, try as many models of as many makes as you can., go up and down in caliber, as much as possible, as well. Ranges rent guns and gun owning friends really like to go shoot (esp. if you buy the gas and ammo.) Use acquaintances made at ranges to talk about their guns. If you are earnest, you may get to try theirs.
Firearms made by, Colt, Glock, HK, Kimber, S&W, Sig, and Springfield among others make quality firearms that are dependable, durable, and reliable once they can be considered to be broken in and any ammo issues are resolved. This is another reason to try experienced guns and use different ammos. Different guns, feel different in different hands. When I buy golf gloves, they are cadet XL (read short fingers.) The narrow grip of the 1911 fits well, as do contoured grips. Some grips (S&W M&P) are adjustable w/ inserts. I find the Glock (21) and the shorter models to be blocks.
Personally , .45acp speaking, I love my Kimbers, I consider my Sig(s) to be the finest made pistols I own, I choose my Springfield XD45 over my Glock 21, and my S&W M&P 45 over the XD45.
Clockwise (from 11 oclock) Glock 21, SA XD45, Sig 220 Carry SAO, S&W M&P 45, HK USP45, and the blade is a Busse Combat, MarcoBolo (Proto)
The Kimbers are Tactical Pro II and Tactical Ultra II