I mostly house rule 5E to get it to work more like older editions where exploration is actually a challenge, combat isn’t a foregone conclusion and slog, etc.
I ban a few races, backgrounds, spells, feats, and subclasses.
I do five-minute short rests, no more than two per long rest.
Potions as a bonus action or standard action. As a bonus action, you roll healing. As a standard action, you heal the max.
I do genre-based inspiration, allow players to spend it after a roll, and let players get more than one at a time. Haven’t settled on the number. Prof bonus, double prof bonus, something else.
I’m also leaning hard into the idea of gritty realism when out of civilization or as the default all the time.
ETA: I also use verisimilitude over rules. You take a swan dive off a 200ft tower, you die when you hit the ground. I don't care how many hp you have. Take a lava bath? Time to roll a new character unless you're resistant or immune to fire. I care way more about the world and the fiction than the rules. If the rules get in the way, chuck 'em.