My two cents...
I'd start with a .22; but for a first center fire pistol, go all steel, not plastic. Go 9mm, ammo everywhere, and reasonably priced. My preference for an all steel 9 is a CZ; great trigger, reliable and beautifully made. I started with a Norinco NZ85 (a CZ clone) as my first 9mm, with the intent that if I liked it, I would "upgrade" to a CZ. 4 years later, and having tried a few CZs, I am still shooting the NZ85; it is accurate, reliable, and a pleasure to handle and shoot. Very well finished as well.
My first .45 was a lightly used Nork 1911 in satin chrome with adjustable sight; I still have it too. It is also well made, tight, accurate, reliable and comfortable. However if you don't reload, you won't shoot it much unless you have lots of money for ammo.
I also shoot .40 S & W with an all steel Jericho (really nice CZ Clone), and as with the .45, if you don't reload, ammo is expensive.
I had a Nork 9mm 1911 for a short while, and it worked well, but did not shoot as acurately as the NZ. Nice pistol though, and very low recoil.
Sigs are nice too, best decocking system ever, and accurate. The ones I have shot are a bit big for my hand.
Lots of choices, handle them and figure out what you like; and get it.