Best Build-Up/Worst Payoff?

What story-line would you say had the best build-up, yet had the worst pay-off in the end? I myself would’ve voted for the whole "Who is stalking Undertaker’s wife Sara?" in 2001. After it was revealed to be DDP, the whole thing went down the shitter fast.

​Take your pick from 1999, but if anyone can find a more terrible example than the Higher Power than I would have to call them a LIAR.​