Indeed the different guilds would be a very interesting option. Not only to get new skills but also the way to unlock the new classes. You go to a guild, train so hard you get specilized to that guild content, being then promoted to that guild's class.

About giving attetion to AoE...well, that's MRD specialization. It is the current AoE specialist class. That's why i said i'd build this suggestion based on MRD current patterns, assuming it as AoE specialist, heavy stanmina user, damage dealer/crowd controller role and pirate background.