Don't play death a lot but this season I rented a summoner and actually did the death quest once or twice..
There's so many tank options that all have some good points which makes it hard to chose any. Harklaw, haunted spirit, pelacor deceiver, got a gold lvl 4 nightmare and then there's that other flying unit.. always a tough decision.
But what I like most is the many strong backline ranged units with lots of hexing. My favorite discovery this season being dark ferryman, bought some to get it to lvl 3 and with cripple and 2 damage I think it's really overlooked. Helped me win some tough matches!
I almost always use Haunted Spirit.
!PIZZA
Think I prefer harklaw now since I never got to leveling spirit, or nightmare since I got a gold lvl 4. But it really depends on the ruleset