I'd probably go for something simple in terms of a ruleset. Maybe something custom and more mechanics driven. It's something I try to do when I write encounters, I set up mechanics players have to figure out in the encounter. And they can advantage for successful mechanics. I also sometimes add 'enrage triggers', so if somebody does something, it puts them at a disadvantage. I feel something mechanics heavy would be a good representation of how encounters in the game work. But of course they have to be the inventiveness of the DM because having any premade obviously means can learn them and just exploit them.

I think DnD is one of those system's that's great but I think maybe, at least thinking about my RP experiences in 14, that it'd be something that'd get too bogged down in the details, though I am aware a homebrew system exists for it.