Which class in everyone’s opinion has the best fall to the Darkside or redemption to the light, kind of like Anakin to Vader in Revenge Of The Sith or Vader back to Anakin at the end of Return Of The Jedi?

I wouldn't have said that any of them have such an arc, to be honest.

Which class in everyone’s opinion has the best fall to the Darkside or redemption to the light, kind of like Anakin to Vader in Revenge Of The Sith or Vader back to Anakin at the end of Return Of The Jedi?

 

I'd argue the Inquisitor or Warrior can be played like that if you factor in decisions made through the expansions and played mostly light-side. I had my Inquisitor gradually question the dark side beginning with that side quest for the Dark Temple on DK where you encounter a holocron of a light-sided Sith who teaches that "Fear is a Lie, there is only the Force." I also had her say at the beginning when she arrived on Korriban that "a Sith fears no one." So I had her gradually turn to the light with those things as initial beginnings. I also designed her to be a Bastila Shan lookalike which further helped given Bastila's fall and redemption.

 

Also the Jedi Knight story has something of this nature but I can't really go into detail without spoiling it.