Two things you need to decide before you buy a 1911 are what kind of sights you want, fixed or adjustable, and can you live with a GI grip safety or do you need a beavertail grip safety.
Making the wrong choice, and deciding to change later usually will require some professional expertise, some grinding or welding on the frame, and some significant outlay of cash.
I'm a Colt guy. They make a solid pistol and are a good value, but the 1991 model comes with a GI grip safety. I can live with the GI grip safety, but you need to see if you can live with that before you buy. The percentage of guys that need to have a beavertail grip safety is very large. If you find out later you don't like it, expect to pay somebody to grind your frame to put a proper beavertail grip safety on it.
For quite a while lots of guys have been recommending the STI Spartan (and I believe the Trojan is now only available with adjustable sights also) as a good value in the inexpensive range, and the Springfield Range Officer at a slightly higher price/quality point. No doubt both are good values, but they both come with with adjustable rear sights. The slide cuts for those adjustables are very different than the cuts for most fixed sights. I've tried to warn guys, and it's taken longer than I thought it would, but the posts from guys saying "hey, I love my Spartan/Range Officer, but these adjustable sights are uncomfortable for concealed carry, or I'd like to get night sights, or dot sights, or the screws come loose, or they broke, etc", are finally starting to show up in significant enough numbers for it to be noticeable. Harrison Design and I think 10-8 Performance make fixed sight options, but if you really do want fixed sights, get them up front you'll have a lot more options.
mnrivrat wrote
In a used 1911 remember that it is the type of gun that sees a lot of cutomizing work. Some of that work is not well done.
This is an excellent point. Since most of you guys have spent just about your entire lives in the "Glock/AR era" they all think if there is a part out there for my weapon all I have to do is buy it and snap it onto/into my gun. It doesn't work that way with a 1911. The stuff you see guys doing or at least trying to do to their 1911's on the various 1911 forums is truly scary.