It's a little surprising with the obvious Ad&D beginnings of Hackmaster... but the crunchiness of it's "All the Whistles and Bells" critical tables actually puts RM to shame. Though, because of them, I find Hackmaster combat actually becomes tedious... so many tables, just for one roll... I played/run it for a few months, the criticals were the first thing we got rid of!
Harnmaster, for me, is a much, much more playable game. Far less page-flipping and the combats are more realistic.. for that reason crunchy, but not hugely so... the virtual absence of levels...and effectively also classes, makes it feel more Runequest than D&D.
Rolemaster. Obviously a personal favourite. I'd say it sits comfortably inbetween the two on the crunchiness scale. If it didn't exist, then Harnmaster would be my choice.