Viconia- get her a belt that makes her stronger and give her flairs or maces, she was a good close up fighter that helped my other more powerful warriors when I did that.
Its not her strength its her totally pathetic constitution. Her hit points are just to low to put in the front line, especially since if she is your only cleric, youd be ****ed if she died until you get a rod of ressurection.
Korgan- work on maces and flairs?!? give Korgan the max skills in hammer before you give him a new weapon since you can use other powerful hammers out there as well as the strength changing one that sets your strength to the max, while that gets weaker in TOB it's still worth it from the added attakc bonus for being so strong. also Korgan is very hard to get for a starting party from all of those level draining undead in that area.
Flail of Ages, Crom Fayer, Mace of Disruption. I suppose Crom is the best of the 3, but its a shame to waste the Mace of Disruption and Flail of ages. An argument to take Minsc along with Korgan I suppose so you can have all 3 used.
Mazzy- Mazzy is NOT easy to get, and the quest that's with her is a big one before you get her (and think of how hard it was the first time for you) also the dragon in the dungeon that has some must have items on him is not easy at all without the proper stuff. I've never used Mazzy but I think that she's not that great of a fighter. she has her weapon skills in all of the wrong places, she's more built to be a thief then a fighter.
Her quest isnt hard at all provided you have +1 weapons and use the ward stone. You can always come back for the Dragon later. To say she isnt a great fighter is pathetically wrong. She is a wonderful fighter. The only shortcoming is possibly strength which is easily remedied in this game. She has good hit points (more then Minsc) and great dexterity. What else does she need to have? Plus she is versatile. She can fight in close or use one of the wonderful short bows. Some situations call for range, others dont.
Valygar- true you can get him early BUT he does have a very hard quest that you have to do or else he will leave your group. that quest can be very hard and almost impossible for a brand new party.
By the time you get Valygar you should have done the Circus tent, Slaver stockade, Skinner murders, Mar'Vars Guildhouse, Umar Hills and Nalias keep, all within a matter of days (few hours play time). You are more then capable of handling the Planar Sphere then. The Clay Golem is the only thing thats even tough really. If you can kill the Clay Golem and have a spell caster who can cast breech, its not tough at all.
I think that a party with Anomen would be good since he's a priest as well as a good fighter to. he has no quests required until later and if you pick the right choices you don't need to do any fighting for Anomen in side quests
Anomens a good choice because he can fight pretty effectively. However, I think its just such a waste to have two Clerics, especially since I barely use one except in emergencies. Personnally I would have taken Anomen over Viconia, but then he wouldnt have a romance so, whatever.
Edwin would be a great mage and his quest needed to get him would be easy with the exception of the golems in one room but they can be destroyed by most party's.
I consider Edwin the only "must-have" character in the game because no one can recreate his spell casting poweress (due to his unique amulet). But then with Imoen and a PC spell caster, that would be 3 essentially pure mages. The more fighter heavy you are, the easier the game is, so 3's a few to many for a first time through.