Some things to think about, and depending on what fuel you are running now. Are you running pump gas currently? If so you could run more timing with the e85 and could make more power NA and would be safer with the nitrous.
Also something to take into account. Do you have the fuel pump and injectors to run E85 without running out of fuel? With the increased need on pumps and injectors to run e85 make sure if you don't have these that you will probably need to get them to even run NA. Also you have to have more pump for e85 with that wet kit as well.
If Daily driven is E85 readily available around where you live and if not do you have a tuning device to be able to change over tunes if you cant find a e85 gas station.
Converting to E85 can have a great power advantage if you have the ability to run it. If you do then go for it. If not running 100 is a good option as well.
It boils down to the convienence factor. I have a pump a few miles away from me so I am going to run E85 and a Vic Junior spray barred intake from Nitrous Outlet. From what I understand the E85 is going to net more power all day than the 93 and it costs less than 93.
Before we had an E85 pump here, some turbo boys would by 55 gal drums of it.