This topic is great, right up my alley, but I haven't responded for fear I'd rant and talk about every memory I have since 94 or so.
I don't know how to personally quantify which classes are best, or how to rank them. I probably have different answers for different criteria.
What I will say, though, is that Gordon + Okafor is tough to beat for me bc BG is one of my personal favorites, Mek might be our most dominant, and they have every aspect of their résumés to stack up with other classes (individual/team/NBA/etc) ... but look at some of these classes. It's also crazy to think how good some of those classes would have been had some of the highly thought of guys had panned out better (Hazelton, Marcus White, etc etc).
As many have said, Bazz class will always be amazing and a personal fav w Bazz/Giff/Lamb all players I love individually plus their 2 rings. Rays class, Donyell's class, Rips class are all obvious great ones, but I also didn't quite realize bc of differing situations that AJ/Rudy and Taliek/Caron were the same classes.
Calhoun had some serious recruiting suction in the late 90s through the later 2000s. I really didn't follow recruiting rankings too much until later, but I remember the most excitement over the Stanley/Kelly/Wiggins and the Daniels/Boat/Drummond classes, yet they probably are the bench marks for not living up to expectations... Interesting and also an important note for recruiting ranking discussions.
Often times rankings don't equate directly, and guys exchange roles as far as which players become stars and which disappoint relative to expectations.