if played to the max capacity:

1) monk
2) summoner
3) dragoon
4) black mage
5) bard

the micromanagement of the pet and dot from the summoner make it harder to play than dragoon, the trouble of the loldrg are about the people using jump or screwing them own cycle... they are simply bad player or people with not enough training for use the class, but in term of difficulty the dragoon is not really hard.