Well, in stock form, all of them have equal horsepower. However, the Loctite Zexel has the most Torque.
I also found it the fastest in a test I did, where I did 10 laps with each JGTC on the same track and the fastest of them all was the Loctite Zexel GTR. It had the fastest single lap, and it had the fastest average lap by 0'00,200 roughly. I dont drive any of the JGTC's regularly, so I figured the test would be somewhat accurate and fair.