what is there to like about this classes?
which is hardest/easiest?
which is most powerful?
pros/cons?
i like long quests and having a big challenge to acheive high ranks and i like i being the center of a attention and a leader

It's honestly hard to say. By the time
you're level 85 - all classes have their upside.

Be whatever you want.

I'd go with Mage though.

These are "at the moment" reviews, i.e. they only apply to what classes are at the moment, not what they were or can be.

Mage: The class can be pretty versatile. The opportunity to completely lock down mobs in PvE with Polymorph, and the ability to have huge amount of damage output--both single target, and AoE.

Priest: By far the most tedious class to level. The ability to heal, at the moment, the strongest single-target healer. Shackle and Mind Control (hopefully just when/if you're Shadow).

Druid: Huge amount of utility with this class. Moderate amounts of damage output, Entangle (effective melee crowd control), and Hibernate (effective beast/dragonkin control). Great healer, effective on either tanks or raids. Great tank, mitigation could be improved, but threat can be solid.

Warrior: Arguably, the most difficult class, but also one of the strongest. Warriors are dependant on others, in the sense that they are useless in PvP without a healer, and have very few abilities to keep themselves alive. Their tanking attributes are, by far, the best. Greatest at mitigating damage, worst at holding AoE threat.

There are always trade-offs, but I would go with a Warrior for what you're looking for.