Here is a little guide to help you understand better what does which Invader offer.

Of course, the percentages correspond to the legendary rarity for each equipment.

Lynx: Defense set

Saracen: Offense set

Royal Guard: Invaders set

Hounds: Scout set

Celt: Melee set

Serpent: Ranged set

All others are all around. Some invaders provide equipments with unique bonuses. For example, Khazar is the only invader who boosts training speed (but only his helmet and weapon).