i just finished powerleveling my latest character, a scoundrel healer, now i lack a sniper, a sage, a sentinel, a vanguard and a mercenary, any suggestions on what i should level first?

Merc its so much fun plus you pretty much burn thu everything in lvl 11 gear till alduraan by that time I'd say gear up but use your legecy move to kill bosses and I feel you good to go. Unless you want to choose another stealth class and just sneak past everything. Btw go pyro