Pistols are like pipes. Pretty much any major manufacturer (and most of the smaller ones) will build a reliable, durable, accurate firearm. I suggest finding a range that does handgun rentals, and try a few yourself. The difference in ergonomics, dimensions, and firing behavior between various makes, models, and calibers is indescribable. Just between the Glock and 1911 you mention there is a world of difference... yet many similarities. Anything from Glock, Ruger, Beretta, Colt, S&W, Sig Sauer, H&K, etc. won't let you down if in good repair, and all can be found (at least used) within your price range. Be careful with the 1911s, some makers are fantastic, some are craptastic, and it's not always based on price.
Even for a big dude size is a concern for a concealed carry piece. Trust me, a big carry piece becomes a damn boat anchor after a while. I know, I've carried a primary and backup daily for the past 17 years and gone through numerous makes/models/calibers looking for the perfect piece. Look at the Glock 17, the 19, and the 26 (standard, compact, subcompact.) My recommendation would be to look at the Glocks, and consider 9mm. Light recoil, cheap ammo, easy to learn, easy to maintain, easy to find holsters and other accessories... and the holster makes a world of difference when carrying... but look at and shoot as many different makes/models and calibers as you can. Glocks are generally reasonable and you stand a better chance of getting a new one in your price range than some other makes... you probably won't find a reputable 1911 new for $600.00 these days.
Right now, personally, I have a Glock 17 for those heavy days, a 19 for daily carry, a 26 for light days, and a Ruger LCP .380 for backup and "a gun to carry when I'm not carrying a gun." 9mm will do anything you need it to do, it's all about shot placement. A mild caliber you can hit with is better than a super magnum you miss with.
I have a fair bit of professional and recreational firearms knowledge, feel free to IM with any specific questions. I assume there are IMs on this forum?
Oh, by the way... the detachable ammo feeding device on a modern semi-automatic pistol is a "magazine", a clip is something different (even if Hollywood doesn't differentiate.)
Good luck with your search!
