Which monster do you like the most in Heroes 5 at level 7?

And what if there's only one, and reinforcements can't arrive in time or are unable to, or if there's a skill to stand until the very end, and if the shots run out (there are only 5, lightning isn't a good option after all – it's weak, not effective, you'll still lose), and there are obstacles in the form of a castle wall or summoned creatures, or something magical falls on its head, dealing three to four thousand damage... these are all minor details. Of course, there are circumstances where any monster can demonstrate its best qualities. A Titan might even be more useful than a Death Knight, or an Angel, etc. A Death Knight is always good. A Death Knight is stability, reliability in any situation – its initiative, damage, or attack won't drop, and it won't unexpectedly fall out of action. It's easy to plan, predict, calculate, and manage the course of the battle.

Added after 3 minutes
This is more important than simply having a larger number of hit points or another improved characteristic...