Personally I would put the best PSU wrestlers in tiers:
Tier 1: DT, Zain, Ruth, Nolf, Bo, McCoy
Tier 2: Wright, Joseph, Matter, Prescott, N. Lee
Tier 3: Hall, Nico
Tier 4: a bunch of guys
RBY, Starocci, Brooks, and Dean are still active so I'll wait until they're done.
Also, the tiers are not meant to be dismissive of anyone. All those guys are incredibly good wrestlers.
Finally, in terms of overall careers -- to include freestyle -- I think DT is in a class by himself.