Sheik, Falco, Fox, Peach, Marth, and Puff have equal(ish) power IMO. I feel Puff is one of the harder ones in this metagame because she's kind of underdeveloped and I don't really feel that the bair wall really works unless you're as good at it as HBox. And then her other base strategies like edge camping and such have obvious counters like angled projectiles (icicles, needles, turnips), Marth's d-tilt, and smart edge grabs into invulnerable aerials (and honestly even though planking is supposed to beat it, lasers generally can get Puff to leave if you're simply more patient or get her to KO%). Her overarching neutral game strategies are polarizing because of punishment potential and various built-in immunities but have pretty simple and safe counters. Because so little works vs her crouch or whatever it can catch unprepared people stupidly hard, sure, but decent players know the Puff MU's basics nowadays.
Sheik, Marth, and the spacies have the most obvious base gameplans and strategic transitions in combat and generally simplistic yet effective punishment trees that set up further punishment, positional advantage, or kills.