I use to run 100 octane before I discovered e85. I have had it tuned for both at one point and can say I believe e85 to be better.
The advantage with 100 though is you don't have to change out injectors to run it. Technically you don't even have to tune for it. With e85 you get the low cost of the fuel but you have the initial cost of injectors, pump and a tune.