if you want a .45 start with a Kimber Milspec. Personally, I would start with a 9mm. Lower recoil and most importantly cheap ammo. I can get 100 rounds for about $12 at my local gun shop, vs. 50 rounds of .45 for $14. Cheap ammo is important because you will want to get a lot of trigger time to help you learn all the basics really well. It took me awhile to become skilled with a handgun....but maybe I'm a slower learner.
So.....9mm suggestions. Well, judging from my experiences, here goes: Glocks, super reliable and high quality. I find them to be very ugly, but many disagree. Also, they have no safety. This isn't a big deal to most but with your first handgun......well don't learn the importance of trigger discipline by blowing a toe off. Lighter than some, this can transfer into slightly higher recoil. Berettas, also a great place to start. I had a 92 Vertec and loved it. No recoil due to it's slightly heavier weight, accurate.....can't think of any real downsides except that it is too big to carry (IMHO). My buddy has a Springfield XD that I've gotten a lot of trigger time on. Great gun, amazing value for what you get, $450 or so for one. Nicer looking than a Glock, reliable. internal safety and loaded chamber indicator (which are neat little touches). Shorter 4 inch barrel but still very accurate. That was my buddy's first gun and he is still very loyal to the XD line. Also, check out the Sig p226. Sigs are quickly becoming my favorite handgun....you rarely seem to hear anything bad about them around here, which is quite the statement. Good trigger pull, accurate, reliable, etc. They are a bit heavier, like the Beretta. Check out the Sig Pro line as well, it's their venture into polymer handguns (like Glock and the XD). Most people seem to really like them and they are much cheaper, around $500 somewhere.
Anyway, I'm sure I could think of more but that will get you started. Good luck man and congrats on your first handgun....won't be your last.