Once I had played the game through and worked out how I wanted to play it, my preferred MM6 party was ACSS. Archer's not as good a fighter as the Paladin, but it does give you at least some chance to protect the Cleric and Sorcerers, and I really did want a party that could use at least some of those lovely edged weapons and polearms, which GP's CSSS can't.
I agree with you about the Druid; he's spread far too thin, and he has no access to the mirrored path magics – unless you play the v1.0 game. There's a "feature" in that which allows a Druid to learn them. Equally, there's another feature in the system that allows a sorcerer to wear heavy armour and wield a dirty great sword, if you want. I seldom used the latter feature, I used the former one more. And never an editor in sight . . . (*evil grin*)
[If you want a REAL wimp, try the MM7 Druid. Once he/she has prepared your party's black potions, he/she is about as much use as a chocolate teapot.]
But once you get the ACSS party up to level 70+ you can carve your way through Castle Darkmoor practically without drawing breath!
APCS is the party for the purist who wans to complete the game with minimal use of the Temples. In addition, it's the party whose members have the best for for the available magic-boosting artifacts. However it definitely lacks the power of ACSS.