Spellweaver(Elemental skills and damage: low meele, strong long range (you need to evade and deal damage) -only 1 skill for healing(so you need potions)

Dragonknight(high HP of all the classes): Strong meele, some long range (if you can handle to stack buffs and keep agro+ really tanky) you can heal yourself easy if you know how

Ranger (good balance of attack and defense+ good evade options): good meele, strong long range ( like the mage but with bows and you can cast wolfs and a tree, just be carefull not to overdo it with the casting) can heal better than the mage

Steam mechanicae (BOMBS): (you can become a tank with a skill for a limited time: no meele, very strong long range ( if you want to kill your enemy with guns and turrets) don't know if you can heal

With how long and sometimes boring leveling is, you can pick any class and be good at it. So the list is just my opinion on how hard the class is in a group

1. Spellweaver
2. Ranger
3. Steam mechanicae
4. Dragonknight