Woould you rather spend 17 points for a prototype with autothrusters or 19 for a green squadron with lone wolf?
Which is a better a-wing flanker?
Depends. What's in the rest of the squad?
Depending on the squad makeup, Pyscho Tycho is very good.
Green with Lone Wolf is probably the better flanker of the two you listed, but like the others have said here, it depends on the rest of your squad. If you have two point-heavy ships, lone wolf will be a little more effective than if you had a big swarm of ships.
Honestly though, if you are bidding up to the Green for a flanker, I would try to fit another EPT on there to make them a little more effective (or even Jake + VI and chardaan). If you don't have the points, just stick with Proto and Chardaan and put those extra few on the rest of your squad.