My ideal party is me, the right girl, and four people who go away
But as for D&D parties, the most munchkinesque (munchiest?) party will be strong in magic. The pure arcane spellcaster and pure cleric are givens, and so important that you may as well take 2 of each. Two wizards can complement each other very nicely; for example, one might specialize in the flashy combat spells while the other specializes in subtler magicks (two archmagi sharing spellbooks... scary). Two clerics are good because you can never get enough supportive magic (healing, buffing, etc.).
A high-level psychic warrior will make a better frontline melee guy than a fighter, because his high-level psionics will be worth far more than the fighter's extra damage. Bladesinger is also a good choice for the main ass-kicker (excellent combatant with some nice spells).
The last spot, specializing in stealth and social skills, is reserved for the rogue or bard, but again, one with strong magic. Arcane tricksters and heralds gain considerable magic without losing a great deal in skills or sneak attack damage.
So this party might look like:
Dwarf Evoker
Elf Illusionist
Human Cleric of Kelemvor (the Doomguide PrC is total munchkin-bait)
Dwarf Cleric of Clangeddin Silverbeard
Human Psychic Warrior
Halfling Rogue/Wizard/Arcane Trickster