For me it was the assault course warmup (This has now been replaced by the determination test). The worse part was is the boots we were given were knackered and didnt fit correctly, by the time I had finished the assult course I had blisters on the blisters on my feet.
I found gym test 2 quite fun. There was no pass/fail criteria expect for the requirement to give 100% effort. It seemed like the 'home run' as far as passing my PRMC was concerned.
Gym test 2 was by no means easy but I found that the different team stances and activities broke it up so the time when quite quickly. I found running over the gym equipment and lobbing medicine balls much more enjoyable than gym test one which may have made it seem easier.
However, my PRMC was in September 2005 so things may well have changed since then and gym test 2 could be much harder (seems weird I am the only one who enjoyed it).