The most useful monster.

It looks more like a rating of strong creatures than useful ones (or with cool combat skills))))
Vampires are strong, but that's all...

:) Yeah, that's true. Vampires are relatively quick to build, and you can get a good number of them. In the early game, even in small numbers, they are useful for developing the hero and the economy, which later allows you to get...

bone dragons with vampirism are much more useful if you consider this criterion))) because angels with resurrection (when you kill a mage hero in the final battle, and he doesn't have time to drink a healing potion a second time) or cyclops that shoot at everyone)) and those who cast slowing spells and other spells)

... everything you mentioned above :) Build dragons with vampirism, repel the spawning of angels or other tricky creatures that cast slowing spells and other spells, acquire artifacts, etc. For example, at the beginning of the game (in the first week), you have the "Sorrow" spell (this spell is indicated for online play; in offline mode, it won't be needed) and the "Slow" spell, and a few Vampires. You need to break through 50 Behemoths that guard something very valuable. You will do it. Replace the Vampire with a Dragon with vampirism (and where will you find such a wonder in the first week?) or an Angel. You won't be able to do it. Well, if you only replace the Vampire with a Fairy. However, the Vampire is better because a couple of Vampires can single-handedly defeat several dozen weak and fast creatures (like Imps) or weak archers.