Handle all of them if you can. Even though they are all 1911's they will all most likely fee different in the hand.
The Kahr (Auto Ordnance) is the most realistic looking though it has a firing pin safety much like Colt uses on their Series 80 pistols. It has an arched mainspring housing. It is made in the US in Massachusetts.
The ParaUSA has the best sights of the bunch. It also has a firing pin safety like the Auto Ord. The reports are that the blue finish on the Para's wears quickly. Flat mainspring housing. Production has moved from Canada to North Carolina.
The Springfield has a good reputation, but does come with the Internal Locking System (ILS) in the arched mainspring housing and uses a unique to Springfield sized firing pin. Made in Brazil.
The Rock Island Armory has a good reputation. The least expensive of the bunch, but typically works well and has a good customer service record. Flat mainspring housing. Made in the Philippines.
I would probably pick the Auto Ordnance, since I like the look better. I already have a "shooter" so I would be choosing for the authentic look. I like the arched housing, short trigger and simple slide markings. I say this knowing that the Auto Ordnance has the worst reputation of the bunch.
The Para would probably be the easiest to shoot well right away since the sights are so much better than the rest of this group. It is the least GI looking of the group though.