I still own at least one example of each of the three sizes. Despite all the internet debate, I've never had a problem with the smaller sizes running reliably. Get what you like. 1911 technology isn't a secret. So, pick the brand, size, and color you like, and go dent a bunch of primers!
Some Kimbers, all .45 ACP
Love this one--I am in negotiations to buy it back from the buddy I sold it to
9mm
Commander in its holster