OP -- most people say "It is the instructor, not the agency" that makes the difference -- and, in general, that is true.
What is it you want to learn? Once you decide what the answer to that question, perhaps all you'll need to do is find an instructor who will teach it to you -- one who has the skills you want and the knowledge and experience to be able to transfer that knowledge to you. In other words, don't look for a class -- look for someone who can teach you and then go take "diving lessons."
The more I do this the more I'm convinced we are way too hung up on "classes" rather than "learning."-----
Re vertical vs. horizontal ascents -- IF one is in a wet suit, pretty much, so what? OTOH, if one is diving dry, there is a huge difference between trying to ascend vertically as opposed to horizontally due to the venting of the suit. A longer (not necessary 84 inch) hose makes air sharing horizontal (neutral/slightly buoyant) ascents MUCH easier.
Re gear and the "GUE Way" -- WAY too much is made of the gear issues and the "integrated nature of the parts" of Fundamentals IMHO. Yes, the "GUE Way" is an integrated system but one can learn an awful lot by just learning some of the pieces -- or learning them piecemeal. You do NOT need "tech gear" to learn non-silting kicks (although one might need paddle fins!); you do not need to learn non-silting kicks to learn gas management or minimum deco strategies; you do not need to learn any of those things to begin to understand situational awareness; and on and on. Don't be put off on learning something just because you won't be able to learn everything.