OK. Star Legends morphed out of pocket legends so I'm going to base it off pocket legends So an
Operative = Archer
Engineer= Enchantress
Commando= Warrior

Ok what I learn in pvp is that the Archer is the star because he defuffs his opponent and reduces armor. Playing a engineer it is similar to playing an enchantress so I would have to guess it's the same as Operative so i would think an Operative.

That's just me though