Best shield in the game in your opinion

Crap for turtling, but for taking one hit, it is fine. 80% damage reduction across the boards, and the weight can't be beat.

But, as Rant said, the best shield is heavily dependent on your build.

Dark hand or heater shield. Depends on the situation.

Grass Crest Shield when 2-handing a weapon.

No shield.

Bone wheel FTW!

I use obscenities as my shield in Dark Souls. It seemed to make Ornstein and Smough rethink their stabbing of my hiney parts in NG +

Silver Knight Shield +5 is made for turtles like me though. If I could transfer the amount of damage I've hidden from behind that thing into actual damage dealt...I'd one-shot Four Kings every time.