I work on 1911's on a regular basis customizing them. Of the list you have, I own 3 Rock Island Armory pistols, as they're an excellent basis for a custom gun. And yes, all of mine are customized, mostly (Videcki) trigger jobs, reliability package and custom finishes. I have a 3", a 4" and a Widebody 5".
A gentleman above said the Charles Daly's are the same thing. They are not. Both Charles Daly and RIA get their frames/slides from Armscor and these are a good basis for a pistol, as they're CNC machined for very tight internal/external fit, but Daly cuts quality and uses oddball and typically badly fitted internal parts, particularly springs, on their pistols and have an quirky warranty.
The RIA's are extremely well fitted and have very well fitted barrels and barrel bushings, items that are very much human dependent. About the only weakness they have is they come extremely tight and absolutely require a 500 round break in to loosen them up.
I wouldn't take a brand new one into a competition, as the tightness tends to make them jam until 500 rounds go through them and break them in. After that, they smooth up, run and outshoot most other brands out of the box pistols.
Because they're well made and well fitted, they're an excellent basis for a custom gun - small internals need to be replaced by far the least of any pistol I work on. Their price point is low enough, you can have one customized for about the price of many other brands off the shelf badly fitted pretend custom stuff. And yes, there is a difference between gunsmith hand fitted and factory worker fitted when it comes to customizing a pistol. A factory worker with a shift quota can't fit as closely as a gunsmith, who is paid for the job, not the quantity turned out.
Colt - good steel, tend to be very loose and internals small parts are mediocre quality and so so, sometimes badly fitted. I've seen many base models with a plastic mainspring housing in the past few years. These are a good model to build a go to war gun, as the tolerances are loose enough they aren't likely to jam, once they've gotten a reliability package, a trigger job, replacement of any crap small part and a steel mainspring housing. Takes a lot of parts to get these to shoot some times. Parts you don't need to replace on the RIA's. Such as a barrel bushing, extractors, slide releases, ejectors, thumb safeties and an occasional barrel. Wouldn't be my first choice for a competition gun - too loose. But, because the prancing horse on the side, you can resell them at a good price once you find out your $350.00 RIA you got to try out just outshot your Gold Cup. (Yes, I've seen this happen, much more than once.)
Para Ordnance - Middle of the pack as as far as tightness goes, but make a good basis for a custom pistol. Prices are higher than the RIA's and don't offer anything much the RIA's don't in a 1911. If RIA wasn't available, I'd use their high cap version. I don't like the gadjet triggers they came up with in some of their pistols.
Rock River - Don't see a lot of their pistols come into the shop, so can't comment on these. Their rifles are generally excellent and their warranties and customer service are good for the rifles.
Springfileld - Good steel, fairly tight, but not as good as they were a few years back when they were made in the states. Internal parts are very inconsistent, sometimes badly fitted. I've often see pistols that need the plunger tube restaked because it wasn't done properly at the factory. I also replace some small parts on these guns with others while fitting custom parts. Overall, good resale value and good basis for a custom gun, but you'll need to buy parts that you wouldn't often times, due to variations in small part quality.