IMO the Bard is the strongest class in the game at low level, if built correctly.
A first level bard can have a 16 Strength (which when combined with their own song, grants them a further +1 attack/+2 damage for about the same results as an 18 Str melee. They can also have a 16 Charisma and the Charm Person spell, which is phenomonally powerful throughout all of the Harbor quests. Not to mention, their songs benefit allies too, not just themself.
At level 2 they gain Cure Light Wounds - making them even better at helping the party and keeping themself at a solid hp total.
At level 4, and this is most important, Charm Person starts to lose some of its lustre (due to you encountering Ogres, Giants, Trolls etc). That's conveniently exactly when the Bard gains the spell Suggestion. Now you can fight like a melee, and bring better crowd control to the table than a Sorc can, and buff, and play a (very) secondary healing role.
So from levels 1-5, IMO a Bard is the best crowd controller, the best buffer, a solid melee and a mediocre healer.
At higher levels, you start to lose a little of this power. Clerics streak well ahead of you in Healing, and you can't come close to keeping up. Sorcs and Wizards surpass your crowd control skills and gain mass damage spells like Firewall, and unbuffed melees become as good as you are selfbuffed at fighting. But, you remain the king of buffing.