Up2Vex there is a long discussion somewhere where we compare each current framework and outline why Mithril is still the best choice for Flarum. It all comes down to the ease of extending through extensions.
I'm unable to find that discussion though 😅 I'm not sure whether it was internal or public, and where we published it. Maybe another Flarum member will be able to link it.
After that research the decision was taken to update Flarum from Mithril 0.2.x to 2.0 instead of changing frameworks.
