Which Hero from Heroes of Might and Magic III is the best?

I, to put it mildly, doubt that crossbowmen under Orrin will be better than snipers. Well, wizards might be better, but snipers? Unless there's no money for snipers, then the logic is clear.

Well, the "Tazik" is good for its own faction, good against the Swamp faction. You could put him in some kind of "Rampart," and he should fight well. But the "Citadel" is an attacking castle. I wouldn't risk, playing as the "Citadel," trading Krag for Taz.