Tough call, both are pretty good options but I would probably go with the wider R1.
I've raced on both and have hours and hours on the R1 in the Ford Racing Mustang Challenge Series as well as winning the overall Redline Time Attack and setting their track record there on the R1, granted that was the first weekend the car was ever taken out and it was far from set up, it was a good tire and should have decent longevity.