This was my favorite thread on the old r/OSR. So is your favorite system/systems?
I’ll start:
Basic Fantasy - BF gets overlooked a lot because the print books are sold at cost so I think it ends up being a lot of peoples introduction to OSR, but I keep coming back to it. The modules are really well written.
Old School Essentials - Just got the Rules Tome and I love it, though I haven’t had the change to dig into a game with it yet.
I have been with one group who runs DCC and they manage by heavy house ruling. It’s a great system but there is a lot of stuff that can be cut out in favor of a good game flow and I get the impression most people snip out chunks like that.