I came from MyBB. I was actively developing there for a while, I'm just not really happy with the direction that their large 2.0 release is going, so I left the community. They're not really doing anything other than making a free alternative to vBulletin, Xenforo or any of the other commercial products on the market. No standardized MVC framework and still the typical static page reload instead of using a proper front end engine like Angular or React.
I ended up wanting to go for a more simple approach, myself and my house mate started using FluxBB and loved it, but just found that it's a fairly old piece of software. Nothing wrong with it's capabilities, but we were hanging out for the next major release which seemed to be taking forever.
I actually found Flarum by mistake. Not through FluxBB or anything, just stumbled upon it recently when reading some threads on another forum I frequest regularly.
I think I have to agree with @Dominion on this one. The minimalist approach @Toby and @Franz are taking, but keeping their minds open for extension development, is why I'm here. They are taking the time to innovate the way forums work, and not just recreate the other products on the market with newer web technologies.