I am the proud owner of four Colt SAA's: Two are 1st Gen BP fame .45's, one is a "Pre-War" (pre-WWI in fact) .45, and between them all they encompass the three standard barrel lengths. I adore them, shoot them, and they are smooth as silk to use. I also own one 3rd Gen. Colt, a Sheriff's Model which was made in the mid-1980's, and is my every-day concealed-carry gun. It's a tad rough by comparison I must admit, but I love them all, and plan on never parting with any of them.
That being said, if I was starting from scratch, I'd probably get a pair of USFA's. The one's I've handled have been absolutely superb, and I kick myself for letting one go (complete with spare cylinder!) that I could have possibly afforded had I hocked something, but I was being financially prudent at the time, unfortunately. Ah, the one's that get away! I still occasionally kick myself for that one.
Hearing what some of the latest posters have said about the new Colts is encouraging however, so who knows. But as a Colt fanatic, I wouldn't sell the USFA guns short. For a shooter that is just a flat gorgeous, smooth SAA, I do admire the USFA's.
Bottom line is, handle both of makes, and find one that you like and fits your budget. To hell with resale, since you're going to be hurting the resale value of a Colt by shooting and carrying it anyway. Buy what feels best in your hand, shoot the bejeezuz out of it, and enjoy it!