The ones people say - goal differential, team save%, PDO.
I'll throw PK in the mix, especially playoff PK. Lots of shitty or pretender teams have had a good PP, very few winners have a bad PK. It's obviously not perfect but there's some trends.
First bracket regular season, second postseason.
2023-24: Florida (6th) (2nd)
2022-23: Vegas (19th) (12th)
2021-22: Colorado (15th) (7th)
2020-21: Tampa (4th) (4th)
2019-20: Tampa (14th) (5th)
Average: (12th) and (6th).
Good teams know how to lock it down and keep their eye on the tiger when the games get tight.