Which heroes in Heroes of Might and Magic III are the easiest to play through the game with? And how can I determine the number of units in a stack?

Wow. I remember that about 10 years ago, I struggled the most with The Shadow of Death, but The Restoration of Erathia seemed the easiest to me. And with Armageddon's Blade, everything went smoothly for me.
In the early versions, you couldn't choose the difficulty level; it was only available at 200% towards the end. But in The Shadow of Death, you choose the difficulty level yourself, either starting with a pawn or directly with a king.