My vote would be for the R1 Enhanced. I've yet to see something about the SR1911 that impressed me. Just kind of a plain gun in my opinion. The black finish on the controls looked pretty thin and cheap to me.
Handled an R1 Enhanced at the LGS the other day and I was pretty impressed with it. Fiber optic front sight is a big bonus for me. If you've never used one, you're missing out. You can also get one with a threaded barrel for a suppressor.