I have many guns. I believe that the best handgun to start off the hobby with is a double action revolver, such as a Ruger GP100 or one of the large frame Smith and Wesson's. The best caliber to get is 357 magnum. The reasons are that, starting off, it's more rewarding to be about to point and shoot, and not have to think about racking the slide or fiddling with a safety, or removing a magazine, or making sure that there is not a round in the chamber after you have removed the magazine. A revolver is point and shoot -- you can practice getting really comfortable handling it, always pointing down range, never pointing it in an unsafe direction, etc.
I say this from experience -- get a full sized revolver as your first weapon, and a semi-automatic pistol as your second. You will always be able to use both anyway (a revolver makes a great weapon for the home to keep loaded in a hand safe, no magazine springs to wear out, and you don't have to decide whether to rack the slide in the dark if you ever hear something).
If you get a semi-automatic, I'd get a Sig Sauer. They are premium quality, and I like the rare de-cocking mechanism that Sig's have. You can chamber a round, de-cock, and then fire them with a double action (full trigger pull). Sig's can fire from un-cocked double action, and then each subsequent shot is single action. (Or you cock and the first shot is single action).
I'm not a fan of Glocks. Don't get that as your first.