well i personaly favor the thief as 2nd class
not for the features, but for the skills
i found it rounds up the character far more,
especialy the very! powerful skill: "use magic devices" comes in handy
ever seen a barbarian with base strength 16 / raging and using monk's gauntlets
and he is able to cast spells (scroll based) - i like those restoration scrolls
and i think the druid develops his true powers in the very last levels only
just my two cents