Overview
Depending on how you would like to play the game, here is a list of the best and worst classes.
Healer
The best class for support is the medic. He is well suited for both tankiness and healing so you can heal up everyone in dangerous circumstances. Not only that but you can do damage from a distance. Whereas the paladin has a slow health AOE and a short shooting length AND it needs time to reload.
Nuker
With ease, this role goes to bandit, he shells out a load of damage and is somewhat durable.
Overall
It might be the first plane you fly. Do not underestimate this baddy. Overall the quad is the best for any circumstance. It is balanced for fleeing and damage and helping the team do massive amount of damage for brief periods of time.
Tank
Lets be honest, a tank is not going to really benefit the entire group. However, if you are all about surviving pick the hog. Nothing wrong with this plane, its ability grants absorption for a brief period of time and it allows you to dive and get some damage or even escape without taking much damage.
XP gainer
The siege tank hands down takes this spot. It has the ability to remove bullets, shoot from a distance, move with versatility, and be a sexy boy. MEANING you can do damage to bosses without getting bombarded and play defensively while not having to risk like the Paladin has to in order to get that hot loot.