I like GIMP. All its features are straightforward and accessible and make sense to me. For this reason, I like it more than Affinity Photo (can't wrap my head around showing or hiding different features based on what "persona" you have active).

There are rough edges. The name, for one. The save/export fiasco. One of the transform tools recently became completely broken. But anything I can imagine doing in image manipulation can usually be done in GIMP with a minimum of fuss.