There's an old adage we used to have.
 Fighter bests rogue. Rogue bests mage. Mage beats fighter. Afterwards the cleric heals them all.

The bard is unique enough to escape that. 

Mind you the scariest group is the all cleric group. They can wear down anything over time thanks to cures, have buffs that can make them decent fighters, antimagic spells, natural undead control and decent armour. They're just not very subtle.