rpg

• Fantasy: Mostly anything other than D&D if I'm the one running it. I'll play D&D all day long, but I prefer not to have to run it. Magical Kitties Save the Day is fantastic, very well thought out and incredibly easy to teach, learn and run. Though it is best for it's specific setting, I have attempted a modified version of the system with "converted" D&D characters and it was an absolute blast.
• Fantasy (take 2): Mazes is another one I really like mechanically, though I have yet to run it. Based on reading it and watching actual plays: the mechanics in it are, simply put, elegant. And it allows for super easy/basically instantaneous conversion of old D&D modules/dungeons/monsters if you want to use those.
• Supers: Wild Talents - This game has the most unique dice rolling system I've ever used and I love it. Once you grok it, it's pretty fantastic. Similarly it has an insanely flexible system to build any kind of powers you want, but in a structured, semi-balanced way. It definitely takes some getting used to for how completely different everything is from any other system I've ever looked at, but it's very well put together and flows really well after a little practice.
• Horror: Dread is so good for horror games. The automatic tension building mechanic that is the Jenga tower is brilliant. Forewarning: This one probably won't be so fun or even playable at all for players who have limited motor functions in their hands/arms because the only randomizing mechanic in the game is pulling blocks out of the Jenga tower without knocking it down.

I feel like the system word is too restrictive, as games comes with system + setting and it changes a lot the experience, so my favourite games would be.

Space sci-fi Fading suns with it's setting were noble house, poweful church, and guilds having the monopoly on technology struggle for politicla power over the known world

Cyberpunk sci-fi I am a bit split on that one, as much as I love the Eclipse phase setting using a variant of the D100 BRP to build a crunchy system doesn't work. and I haven't tried the transhumaniy fate's version. Therefore, I would say Cyberpunk 2020 which is one of the game I played the most

Modern investigation I would go for Chronicle of Darkness (aka nWOD 2006) it works fine, with and without supernatural elements

Horror Kult the recent divinity lost editions is pretty great, and IMO as one of the best GM section in the PBTA world which really explains how to plan a campaign using a mind-map an using PBTA consequences to make your plot move in the background.

Heroic fantasy Bloodlust which while not translated in English is pretty great. God weapons with their own lust and weak humans fighting to carry them until they find-out that they're the weapon's will toy rather than the other way around. the 2010 Metal edition has also a nice modernized system (with FATE style aspects) and all fitting in one big book

Special award 10 candles as a pretty great zero prep horror game

Special award for the whole forged in the dark family I had great experiences with these systems. While I am less fan of the gang management downtime it's a good modern intermediate between rule light and traditional systems

I mean pathfinder is sorta my current go to but you know one of my favorite groups I was in the dm used the hero system where he used the champions variable power pool for spells so that you can describe to him what you would like a spell to do and he would sorta run it through to see how much mana it would cost and if its doable and would suggest ways to save or such with it. It was a blast. sci fi is tough because I liked playing d20 star wars but also like star frontiers and like d20 babylon five. so the systems made and integrated with the ip were sorta nice. that being said I used to love star frontiers. for superhero I like champions. champions online is actually sorta cool as it uses the rules as a basis for the game which is why you can freeform characters.

• "Realistic" Fantasy: Chivalry & Sorcery
• High Fantasy: HARP
• Space Opera: Space Opera
• Science Fiction: CORPS or EABA
• Dieselpunk: Tomorrow City
• Modern: CORPS or BRP
• General Purpose: Spark, FATE (typically Accelerated Edition), EABA, or a BRP hack

I pretty much hang around the Heroic Fantasy genre, and my thoughts on running it are very different from my thought's on playing it or otherwise. But Pathfinder 2e is definitely my go-to for running. Shit just works. I cannot express how much I appreciate the encounter budget actually being accurate instead of just a vague shoulder shrug like earlier systems.

As far as other genres go... I've run Scum and Villainy for sci-fantasy crime dramas, and it wins by doing absolutely nothing! I'm just not enough of a Sci-fi Greg to run more in the genre, heh.