bought a springfield used but with adj sights, and well put together from a cgn member about a year ago, excellent workhorse. Never tried a kimber, but if one has the extra money, i would go with kimber. agreed that it comes down to what features you want to spend the money on, and comes down to buying the right model rather than do add ons later, at much higher costs.
kind of grew up with diff. 45's over the years, the first one being a colt series 70, which unfortunately was a piece of crap, spent $450 on that but needed a qualified smith and after market parts to make that old girl work right. so i have a lot of respect for the "clones" and "johnny come lately" manufacturers like kimber and springfield
my top 2 favourites are my valtro 45 and a stainless smith 1911 with adj sights, though for the latter, i would have like it even more with the rails. happy shopping!!