Which is better shaman or evolved shaman?

I would say shaman is better because shaman can do alot of dmg also it can heal

Shaman cannot heal fast at all and it only heals it self (not good for a support class), it has mana issues and con only work in a team in most cirumstances.

Evolved Shaman can do progressivly higher damage and DoT this means that given enough time (stun useful for that) it can solo anything that is not immune to a stun.

HOWEVER!

Random nature of Evolved Shaman makes it unlikely that it can keep endlessly stunning.