Just went through a similar decision making process. Also had Springfield, RIA and Colt on the list. The Colt I was looking at had fixed sights that would have required smithing to change out. The Springfield had target sights that I didn't care for. The next model up was $1800 for a TRP, also out of the question. The Colt was nice but didn't feel quite right. The RIAs get great reviews and you can't beat the price. It didn't stack up to the Sig though. The Sig felt like it was made for my hand. Solid build.
I got the Sig, took it to the range, put 100 rounds down with only 1 FTF in the first mag. I'll chalk it up to break in. Very nice 1911. I still want a Colt for historic value but I'll be looking for a used WW2 model when the time comes.