Although I’ve tried quite a variety of rules, the only one I’ve consistently played and kept returning to for the last 20+ years has been DBA. I’ve come to like Big Battle DBA more than the regular games, but for a fast, fun multiplayer campaign you can’t beat 12 element DBA! The final third version of DBA is, IMHO, the best.
That said, I’ll play Hail Caesar and To the Strongest for the occasional change. (I actually like HC better than its predecessor Black Powder, but for some reason I can’t quite articulate, I like the ECW “For King & Parliament” more than its predecessor TtS).