Some years ago I reluctantly switched back to Cabal for reasons I won’t get into, lest I again summon the beast.
Since then I’ve seen it steadily improve in reliability and usability. But it still has a long way to go.
Switching is usually a matter of running hpack one last time, learning about the latest syntax of Cabal files to clean things up, learning about Cabal projects to recover a lot of the features I (for one) needed most from Stack, and just using cabal build, cabal test, and cabal repl. Plenty of things are still easier to do with Stack, and if you run into one, I hope that there is an issue about it. If not, please open it.