Easiest one to adjust to, I don't know. May be the PS85.
But the hard one would be Pacific 90. But if you're able to consistently hit the center, fit and quick to play like an all-court player, it's sheer bliss, esp with the right string set up.
PK REDONDO TALKS & INTERESTING LINKS REGARDING REDONDO:
Making a Super Redondo:
"Don't play what's there. Play what's not there." -- Miles Davis