I'd also recommend a Glock 19. It was recommended three times in this thread alone by other BOTLs. My G19 has had all sorts of different "quality level" ammo thrown through it and has always been reliable. It has never jammed up and is very forgiving on the maintenance side.
If you are going concealed frequently I'd take a look at the G26, which Starchild mentioned. It's slightl smaller & the pinky extender for the clip is must IMO. I've debated about switching over to one but don't want to spend $ on another sidearm right now.
You could also do what elderboy02 rec'd, snag a .40 glock and buy the 9mm barrel for range use.
IMO, a lot of it is personal preference. Set a budget. Then you need to decide a primary caliber choice and go a local range and try shooting their rentals to see what sidearm works best for you. If you are going to carry concealed that's another aspect to take into consideration. I'm only 5'9" and 140lbs, so for me to try and rock out even a Walther P99 and have it hidden is going to be a challenge depending on what I'm wearing.
Sigs are awesome too, very accurate. Still, for all around use and reliability, my vote is with any Glock.
