Did UPT. And I did civilian CFI before the military equivalency test was available. UPT was way harder but for a lot of different reasons - one year long, evaluated every minute even when off duty, little chance for do overs, volume of information etc. But the CFI oral and check ride were actually hard too. CFI you could take as long as you wanted or needed to prepare and if you fail just do it again. No limit on do overs.