I prefer assassins to 5000HP tanks
There is a difference between a good assassin player and a bad one, a good one will flank and find opportunities to blow up your squishes. A bad one will jump into your team 1v5, get CC'ed and die.
Meanwhile 
go around with 5000HP, 200 Armor and 150MR and still oneshot your carries. And they can't be blown up.
and his low CD E.
can save you from the assassin while you kill them.