Yeah Fighter is king of giving and soaking damage if built correctly, and can become unstoppable killing machines if using Battering ram to get in the fight, Dust devil and Whirlwind to hit everyone around after getting into the middle of them, or Flurry to kill/weaken bosses in one move, Power stance is better than Rage IMHO, less damage but fewer adverse effects. I give scrolls to the fighter so he is effectively a fighter mage, Lone wolf him and max his stats ( STR SPD CON first), defense skills and weapon skills. Fighter carries everything and is also the face-man...you want him up front anyway.
I always build a Rogue/Archer (Wolgraff)...stats for optimization are same for both, Rogue skills are not battle-winners IMHO. Some others have probably used Rogue skills and sneak about more than I do and can report there are other viable tactics that are effective. I use my Archer as a base of fire to support the manuever element ( the fighter). Archers should use Richochet, Arrow Spray, Barrage, and power stance, especially ricochet. Get the Archer Heartseeker and upgrade it as much as possible-sextant, bowstring, tenebrium, elemental essence all can be added making it lethal.
Mage's are good for the AOE/summons spells, healing, and buffing the fighter and rogue, I never de-buff the enemy better to do more damage or buff a party member. Summoning spells, are force multipliers for small parties ( I always play small parties), especially undead armored decapitator and Spider seems to be the best summons in the game. Mage is also usually my crafter, blacksmith and identifier.
I am not nearly so experienced in this game as others but so far I have not done terribly, you can build a character any way you like but a master of all skills or abilities is not going to be great at any of them, specialization is essential. I personally think lockpick, sneak, pickpocket, charisma, barter, telekinesis have their uses and fans but points could be spent better.
Fighters benefit from stats and gear the most( improving a fighters abilities by improving gear is a cheap and easy way to make them more effective), mages from skills ( more spells and high Intelligence makes a mage an arsenal) and rogues need both, although as I stated I under-use the Rogue like skills and abilities. Everyone benefits from high Leadership, which I try to get to 5 on both primary characters.
Many ways of doing things and progressing in the game, more than one answer to nearly every situation, a very strong game with many nuances...I am still learning something new all the time.