===== Dungeon World =====

The one I use is one I made myself, Mixed Adventures. It uses aspects from other hacks that I really liked but felt there was things missing. The most unique thing about my hack, is that the wizard and cleric don't have a spell list. But use a freeform kind of magic limited by schools or the deity's domains.

But if you give Dungeon World a try, I think you should try a "hackless" game first. The game is still decent and it will give you can better feel to of if you think it needs tweaking.

And you are correct. Avatar still uses the same flow as other PbtA games. So any experience with other games would give you valuable experience to run it as well :)

===== Principles =====

I feel like I’ve heard some strong reactions against stuff PbtA from similar circles though. Wonder what the disconnect there is

My take on this, is that the biggest difference between DnD and PbtA, is that DnD fixates a lot on balance and encourages a player vs GM mentality. Like encounter planing is so important, players rolls against the GM, the GM has to come up with twists for characters, etc.

That is a lot of work for one single person. And it has been like this for many years. I can imagine to some people, it might feel like being told to try and drive blindfolded. And trust your passengers to tell you were to go.

I have tried to pitched the open PbtA concept to a primary DnD GM a couple times, and one of them just looked at me horrified and asked: "What about my story? My plans?". Or one complained that it didn't seem fair that the players could decide the outcome of the dice .

But so far, from my own experience, I have never been more relaxed during my games. The openess and inclusivity of the players have lead to some amazing twists and turns in stories. Twists I didn't even come up with. So less work for me AND I could actually be surprised by the story.. Kinda like a player :D

===== FitD =====

That’s the first time I’ve heard someone call Forged in the Dark mechanically heavy

It is also my own take, and as I said, I havn't actually tried a game yet. But when I compared it to DnD, FitD is not heavy at all. It is only when I compare it to most other PbtA games. But when I read the books, they still feel like solid games with some good explanations of the games flow.

Not sure if you have any FitD books, but there is one called Wicked Ones which has a free version of it.