I do still really like the power level system One Piece uses of bounty values, and it's mostly because of how they're not real-time the way scouters are.
It lets you position Power Level updates where you want. The story frequently does so in between major arcs, which is easily achieved with the format of the islands. It's diegetically a measure an existing faction - the World Government - uses to a specific means (bounties are hypothetically something people can claim, after all), and it's not exclusively a measure of their power, but rather of their 'threat', the value the government puts on their being eliminated.
The lack of real time updates also allows for one of my favorite moments, though it's been so long since I've re-read the series I can't remember exactly who it happens with, but it's a character that initially sees Luffy's "power level", estimates him as weak based on that... Only to find that his bounty's been updated very recently to more than triple what he had before. And it's physical, the bounties are on paper and usually spread around the world by like, seagulls.
Idunno, it's fun.
