IMO of the 3 arcane pets, Samael is the best. I don't have the other two and don't have any plans on getting them. If you look at all of the stats you get with Samael, I think he's the best damage pet in the game. +25 primary stat, +10% damage and +10% crit. And if you are a mage you get +10 INT on top of that which gives you even more damage. And you get a 10% chance to instakill a mob. While 10% is a low chance, in elite runs this a huge deal.