I think I've narrowed it down to a toss-up between For Gold & Glory, which captures everything I ever loved about AD&D 2nd edition and then makes it somehow better...vs. Dungeon Crawl Classics, which encapsulates everything weird about sword & sorcery in the seventies....vs. Basic Fantasy, which as Chris reminded me is actually the sort of game I like playing.
Beyond the Wall is still a possibility. I ordered the two books out for it the other day....we'll see what happens when they arrive. I love the elegant playbook design, which superficially reminds me of Dungeon World without also having all the problems inherent in Dungeon World design. Really though the playbooks are like the old lifepaths from RTG's Mekton and Cyberpunk 2020. Except you also have them for modules, which remind me a bit of more focused versions of what Sine Nomine does.
But....yeah. It's going to be one of the above.
EDIT: Still...Castles & Crusades is cooler than For Gold & Glory, insofar as it manages to encapsulate what I liked about AD&D while still making it more flexy in a D20 System way, and still giving you all the classes and races you could want. Gaaaaah. Problem......not.....resolved..... Plus, as much as I love C&C two problems arise: first is that I can't be certain I'm not just overly enamored with Peter Bradley's art, which I love. Second, of course, is that C&C starts to get too close to D&D 5E, which gets me back to begging the question of: why not just continue to run that and stop this madness??? (The answer, of course, is because D&D doesn't have Peter Bradley...)
Yes, it's been a relaxing thanksgiving! Time to actually read game books and think about this stuff. Love it!
EDIT #2: If you're wondering about how serious I am on this, it's "pretty serious, but any solution that leaves me thinking D&D 5E is the answer is ruled out."
For example: C&C, FG&G and most others leave me thinking "D&D 5E is the answer." But there are the three exceptions. Beyond the Wall actually looks very functional as a support module for other systems....so it could end up being something I run with something else. Then there's Dungeon Crawl Classics, which I really do feel is the only OSR product out there which defies convention and captures the spiritual intent of 70's gaming but in a way that is not properly a clone. That's pretty cool...and means that trying to adapt its modules to another system would be missing the point; DCC plays best with itself, basically. Basic Fantasy, on the other hand, might be the best medium compromise: it has the old school vibe, and is minimalist, such that it necessitates taking it at face value; it's pure classic fantasy gaming without any of the tedium of emulation (so, ascending AC is in, for example). I'm keen to try DCC at some point....but for a conventional classic fantasy game, Basic Fantasy is looking like top dog.