So tips:
I hear that mages are over powered, at least more so than other classes.
You can get AoE which creams enemies, and also yourself.
Rogues are weaker... almost too weak. But they have their uses.
two handed or 1H and shield > dual wield for warriors.
To answer your previous question, I main a tank, and really... I only just started so my party choices are a bit limited. Mostly it's two range attackers and two melee. I cleared the zombies and a few random encounters and made my way to the capital city.
Here's my impressions so far:
1. Mages are stupidly OP. I mean... seriously? One minute I'd be happily massacring their entire force and their single mage shoots this tiny green spit at my guys and everyone dies one by one. What just happened? Why did everyone die?
It's quite interesting though as you end up fighting them very strategically, ducking behind cover, splitting up your troops to flank him, etc. Also, he can do a craptonne of friendly fire, so if your tank gets swarmed by low level foes, the enemy mage might help you a lot.
2. Rogues are interesting. The archers have a lot of invaluable skills though DPS isn't their thing. Over time, you'll definitely love them as it's what will save your ass from either hordes of longe range foes or those wolves or dogs. They can also smash enemy armor, get them stuck to the ground, etc. A whole party of archers (give all your guys a long range secondary weapon) makes your life very easy when you need to pick off the small fries around a big boss.
Then there are the assassins. These guys focus on DPS. They will churn out small amounts of damage very, very fast. They are also very, very frail so I tend not to use the guy.... but he is very entertaining to have in a party. Personally, I prefer the archer and you will always need a rogue in your party to pick locks.
3. I think anyone's number one priority is to find a healer. I have no idea where to get one other than it probably is at the mage's tower but your only other source of healing are the little health pack things that don't really heal you too much...