Since you get 6 characters, there's no need for hybrids in general. You can use the specialized classes and really specialize them in their core strengths. By the end your casters will have so many spell slots they'll be hammering out spells every turn and don't need any combat capability, while your pure fighters have the job of wading into the enemy lines and taking out high priority targets (or grappling them).
Fighter is my favorite martial class because of extra feats (if you play with the two feats per level option you can get pretty much EVERY feat by the end, if you play by normal D&D rules you can still get pretty much every feat that's useful) and because of Wade In, which is a feat you get later on that allows you to use your full attack after moving. This is insanely valuable, especially when dual wielding, since it means ANY enemy within walking distance will receive the full 10 or more attacks.
Wizard is top tier, especially lategame when you equip her with robe of the archmage and crown of the archmage, which give +1 spell slot for ALL spells level 1-9. You can use your massive fuckoff nukes every turn in the hard lategame battles which is very important. The wizard gets a bunch of spells that are useful from start to finish. Grease will be your early to midgame workhorse and is a level 1 spell. The level 2 spell web is amazing mid-game. The level 3 spell stinking cloud is the best spell in the game imo because it only relies on a fortitude save for anyone caught within it; spell resistance does NOT negate its effect. Anyone who gets nauseous loses all actions. At level 8 you get a spell that lets you cast spells as a movement action rather than a full action, and then you can fire two nukes per turn. Level 9 spells contain some absolute nukes that can kill or disable entire mobs of enemies in one go.
Psionic is another top dog. Power points mean maximum flexibility compared to spell slots. Low level spells scale upward in power by investing additional power points into casting them. A low level spell that usually costs 1 PP to cast can have 20 PP invested in it to increase its effect massively. The level 1 spell stomp is another workhorse that stays useful till the end, knocking down enemies caught in the cone and damaging them in the process. Has a healing spell at level 2 that is personal but can be used on other characters with a feat, and scales with PP investment. Only the cleric's Heal spell heals more HP than this one. Like the wizard, gets a spell that lets you cast as a movement action at level 8 which means two nukes per turn as long as you don't move. Has some delicious nukes at high levels, not as many as the wizard but still good. And even the top tier nukes can be improved by investing more PP into the cast. Decerebrate is an awesome single-target spell that can permanently remove a strong enemy from the battlefield by turning them into a useless retard who can't act at all ever again unless a cleric uses a top tier healing spell on him.
Druid is decent and has more utility than the Cleric overall. Quicksand is a level 2 workhorse spell that, again, stays useful until the end. Mid-level druid spells are mostly underwhelming tbh, except for the summons which serve as good meatshields and baleful polymorph which is especially useful to deactivate enemy wizards by turning them into toads. Lategame spells are pretty good, including fun stuff like a whirlwind that deals damage and has a chance to stun and earthquake which has a MASSIVE AoE. Gets access to Cleric healing spells and is generally more useful than the Cleric, but I ran with both of them anyway.
