I'm quite sure that if this question was asked in the context of BG2, Inquisitor would win outright, but it seems that there is not much use for it's True Sight and Dispel Magic in IWD, while lack of Priest Spells and Turn Undead leaves it at a complete disadvantage in a game that is literally flooded with Undead hordes.
Blackguard is powerful in it's own right (especially with its Poison Weapon ability), but cannot use a certain very nice weapon.
Cavalier has many nice immunities (including Poison immunity), and inability to use ranged weapons is a small price to pay for that. However, both the Blackguard's and the Cavalier's immunity to fear speciality is made redundant by the Divine Courage ability that Paladins gain by default at Level 3.
Undead Hunter has an immunity to Hold (not considering Level Drain since I haven't found any enemies using it in IWD) and it's bonus against undead creatures is pretty significant from the beginning to the end of this game.
And then there's the vanilla Paladin.
My question is, which one would you recommend for IWD:EE: (1) when playing with a party, (2) when playing solo, and (3) when playing as a good-aligned character?
(Poll choice is just for the best option.)