Which monster do you like the most in Heroes 5 (level 4)?

No, I don't have any favorite Tier 4 creatures when evaluating them based on combat effectiveness. And I didn't try to prove that vampires are stronger than lizardmen. It's impossible to compare them because their combat styles are very different. If lizardmen deliver a focused but extremely powerful attack, then vampires, due to their lower attack potential but greater ability to stay on the battlefield for a long time, gradually weaken the enemy's troops and don't always focus on the same target. This is my subjective view. And which of them is more useful? It's quite debatable. However, for a hero of the same faction, the choice is obvious. A creature like a vampire wouldn't quite fit in the ranks of the Elves. Similarly, with the undead, they specialize in defense and weakening the enemy rather than inflicting huge damage.