_Monk is as easy to solo as Pugilist. Pugilist can use LNC skill to boost dmg, CNJ spell like Stoneskin/Protect as well as GLA skill to increase survivability. On the other hand, Monk has extra Weapon Skill so you have more combo in higher level.
_Lancer is much easier to solo than Dragoon. Lancer has more protection through CNJ spell and you dont use up MP as DRG/LNC as you would with MNK/PUG Fist of Fire/Earth/Wind, so you dont have to be worried about running out of MP.
_Monk is easier than Pugilist.
_Lancer is arguably on same par with Dragoon. Lancer has less damage, but can do support at the same time. For instance, Lancer can raise when the Healer is down.
_Monk is better than Pugilist. You are always in a pt, more damage is better.
_Same reason, Dragoon is better than Lancer. Also LNC/DRG can't stay in safe spot like ARC/BRD/Mages so there's not much point in supporting with Stoneskin/Protect/Raise/occasional Cure.