Step one in picking a handgun: pick something thats popular and is proven itself over and over in high round count, bad condition training and battle. Glock comes to mind, XD seems to be gaining ground, GOOD 1911s also fit the bill. Sure there are tons of other manufactures, but these are tried and true options that at training classes get used by the vast majority of the people with little to no weapon initiated malfunctions when compare to the guys shooting the 'other' weapons.

Step 2: choose the size that fits you needs, both physical size, and caliber, and rent the crap out of it.

Step 3: buy the gun, for ever dollar u spend on the gun and gear, spend at least 2 on training.

Realize that good shooters can pick up anything and can be fast and accurate with it. Any auto loading pistol thats built to decent standards will out shoot the the shooter any day of the week. So generally speaking its US that cant hit the target, not the gun. If you shoot one gun considerably better than another, chances are its lack of skill. If you shoot a specific gun marginally better than all the others, that's natural and called consumer taste and preferences.

Focus on becoming good, not finding the 'perfect' gun. they are all good in general, its the shooter that needs all help.

In short, buy one that has a good reviews from people that actually use them, essentially ignore everyone that goes to the square range. And it should fit your hand and point naturally, above and beyond that, it doesn't matter all that much imo.