If we are talking specifically about 5e, the wrost class is and always has been the Rangers. Yes, they have gotten more comparable due to some particularly potent subclasses launched years after the edition came out, but the power level wasn't the main problem.
The main issue with Rangers is that they are still overly focused in ways that make them unsatisfying to play and frustrating to GM. A Ranger has to be good within a certain environment and against certain types of foes. If a Ranger is good at fighting fae monsters in swamps, the campaign will be about fighting undead in a desert. By the time the Ranger gets enough levels to also become good at hunting undead in deserts, everyone else in the game will be sick of undead and deserts, and DM will shift to dragons in a frozen tundra. The solution that groups have resorted to for the GM to revise most or all encounters around the one aranger character -- or more often players just don't touch the Ranger because it's too much trouble. Some groups have gotten so used to these issues that they don't even realize they are working these problems.
Revisions to the class (like the revised Ranger abilities in Tasha's Cauldron of Everything) addressed this problem but didn't really fix it. It remains narratively narrow.
The Bloodhunter (an optional core class which has thus far only appeared in Unearthed Arcana) fills many of the same tropes and uses without these problematic first level abilities.
I haven't yet looked at the core abilities of new Ranger for 5.5e.