What's your favorite defensive building/trap?
As the title suggest, I'm curious as to what people find their favorite. Given every build has it's purpose (Spring Traps for those giants, Air Defense for them dragons, Wizard Towers for splash damage, etc.) i'm asking:
What is your favorite defensive build?
AND/OR
What do you think is the best defensive build? (Because we all know their different.)
EDIT:
I'll start it off,
My Favorite: Hidden Tesla (it seems i've grown a liken to them. Not only does the x2 damage to pekkas help but they get to a level where they are literally one shooting all the tier 1 troops that come next to it.)
The Best: Inferno Tower (Nothing says "F your healing spell" quiet like one of these)