The strongest hero.

I'll vote for the Warlord.
The others are either weaker than him – like Tieru; or they are newcomers – like Zephyr, a very young mage, albeit a talented one; or Faidaen – an impulsive and inexperienced warrior (a poet and diplomat :D); or they are rulers of states, or guardians of various cults and laws, or mages and wizards who have reached a certain level of mastery.