Depends on the track.
If the club adjusts weights, that will impact which motor is optimum.
I had a Rotax for a few years–the carb was a nightmare. So was the clutch before they introduced the new one. There is no denying the success of the program over the years, however.
In Georgia, the X30 seems to be the one to have now IMO.
Just don’t get a PRD unless the club has a large spec PRD class.