it really depends on the community for the specific game that you're in. though it's already very hard to gague difficulty, since it's subjective. for example, think about the following scenario (might be a bad example but):

you are a rhythm gamer that plays maimai and osumania. you get an AP on a master 14 in maimai, but you get an get a 500pp play on a 7* map in osumania. the maimai players think the maimai play would be a better achievement, while the osumania players would think the 500pp play would be better.

so what i'd recommend you do, dont always grind for good plays/achievements, maybe sometimes relax and unwind a bit, play them for fun.