With little over 1week of experience in gw2 I think you should go for classess that can be still useful when you play simple.Like Thief(daredevil), Warrior(Greatsword, axe), Necro(minionmaster, reaper, scourge), Ranger(2 handed bow, Greatsword), Core engi with lotsa turrets and ranged skills. Of course in the end I think you should try everyclass. you can find openworld builds for mentioned classes in metabattle.