Rule systems that work especially well in PbP

Are there any game systems you've found to work noticeably better than average in PbP (when compared to using other systems in PbP). For systems that are just "ok" in PbP, have you found tweaks that really improve the PbP experience for that game?

(I suspect this may have been asked before, but I can't figure out how to do a good search.)

I'm running Black Sword Hack, which is a hack of Black Hack (itself a hack of OD&D), and am finding the player-facing rolls to be quite simple! Dragonbane was also good, for the same reason!

Black Sword Hack also has the added bonus of having an initiative system where the players test their own skill, and get to act immediately if they succeed, or later if they fail. No strict order.

PbtA games can really sing in PbP. In many ways the PbP can improve many aspects of the PbtA experience. One tweaks is to let the players roll and pick the result of their move -- that can keep the fiction flowing and reduce handling time.

I’ve had some good results with Fate. It’s a more cooperative narrative game I think.

Anything with a clearly defined (and often singular roll) mechanic works really well.

Cairn and the like with their roll under the stat style gameplay.

Warlock! and it’s d20+skill where you have to reach 20 or more is also great!

Anything that stops too much back and forth really keeps things moving!

WR&M
24XX

Lightweight. Robust. Fun.

Second all the games based on The Black Hack, and would add the Tiny D6 and Mark of the Odd games as well.

Fabula Ultima works really well in PbP. Quick and simple mechanics with the option of collaborative storytelling...it handles its intended genre well.

Single roll systems completely remove the to-and-fro, I really find these so useable in PbP. Avoid those with bargaining and conditionals, and reactions can really bog down combat. Change opposed rolls with an easy tweak, just declare a target number beforehand, or make them non-opposed rolls. Group intiative allows whomever is online to post first without waiting for others.