Depends on your gameplay style. For me it is Valkyrie or Cleopatra. For others it may be Scout and somebody else choose Berserker as the best…
Just use best class suitable for you and boost it by perks. For example if you use plasma, go for Elder - Stalker and add Downrange perk. If you like to melee use Cleopatra with Fearless perk and Elder sword/Sickle/Hook. Don’t try to improve weak characteristic of class by perks. Don’t try to eliminate reduced Scout melee damage by adding Fearless perk or improving Berserker speed by adding Long jump.
Or maybe you can find some perk combination which will flip the class characteristics… how about Scout - Analytic with Energy cell, Downrange and Height Advantage for plasma and bow attacks from trees (or Impenetrable if you don’t like trees)?
Just have a fun building and experimenting with your classes 😎