Which level 4 monster is the best?

How will you prove it? Vampires are the best! Snipers shoot once, and the vampires fly in and drain their life!:smile19:

Hmm... it's not really appropriate to compare them in a 1v1 scenario.
It all depends on the situation.
Although, in my opinion, vampire lords are better than snipers.
Why? For example:
In a random XL map, give a level 1 hero 10 vampires and send him to clear out dwellings; he'll slaughter everyone there and return with a high level.