You will probably want to avoid DRG and MNK due to their potential being greatest when they are not in front of a monster. The positioning can be a bit of a nuisance if you do not have a tank with you to keep the monster occupied. You might still consider a tank, even if you don't intend to do dungeons with it, due to their durability which can come in very handy during FATE events (which you will probably be doing a lot of) when you are alone. Warrior has a good mix of damage, durability, and self-healing which makes it a nice melee choice for solo work.