Which level 3 monster do you like the most (from Heroes of Might and Magic V)?

Archers are definitely the best... But you're exaggerating about ghosts. What does it mean: without incorporeality, they're weak? Of course. But they won't be made weak just because all units of a certain level should be equal, so it's a great unit – it's really annoying when you miss them, they're good at retaliating, and they're often targeted first so you don't have to deal with them later, while the rest of your troops do whatever they want.