Sig would be my choice all the way. Ever since Kimber's 1911 guy left them a few years back and went to work for Sig, kimber has gone down the drain and is no where as reliable as they once were. Sig makes one of the finest 1911's you will ever shoot and I would put its accuracy up against any custom 1911 out there any day. Your going to spend at least $900 or so on their less expensive models and up to $1200 or so on their higher end, but no matter which one you choose, they are all one of the most accurate pistols you will ever shoot, and built to last a lifetime.
To add on to the Kimber info, if you do buy a Kimber, make sure it was made pre-2007, anything after that and your throwing your money down the drain.
If you want to spend less than $900, Springfield is a great 1911, and more than $1300 I would go with STI, but I highly recommend saving up for a Sig, you won't regret it, it's my most accurate handgun and believe me I could own any 1911 I choose and I choose Sig.