Tombstone kickout at Mania 27 is a big one. Between the amount of pedigrees HHH failed with, and the symbolism behind the move I thought for sure he'd ended it. Funny story was that despite never being a supporter of these 'HHH is the biggest asshole everz' groups, the minute the ref started to count my initial thought was 'that big nosed bastard has booked himself to win it hasn't he?'...must be a bigger Taker fan subconsciously than I ever thought I was
It might be pretty tame all things considered, but Sheamus kicking out of the AA at Money In the Bank 2010 really shocked me. The whole finishing stretch with Nexus surrounding the ring and Cena looking in trouble, only to counter at the last minute and hit an AA from out of nowhere..it just felt like the perfect finish which made no sense (Sheamus only having won the belt the month prior) and I figured it was their way of hotshotting the belt into the Cena/Nexus feud. So to see Sheamus kick out as I was already lambasting creative for killing another young guy before he'd even had a proper chance caught me completely off guard.
From my younger days, Taker kicking out of the Sledgehammer at Wrestlemania 17 was pretty big. I'd only just gotten into WWF a few months prior, so had no clue about the winning streak (even if it wasn't properly referenced at the time) and bought it as the finish.
There are tons of amazing false finishes in Puro and Lucha, the Villano/Atlantis Mask vs Mask match from 2000 being the obvious frontrunner. An insane amount of nearfalls from pinning combinations and each one was timed superbly and had me on the edge of my seat trying to figure out who was winning. The one true advantage of Lucha not operating in the US style of having 'traditional finishers' and instead having any move be capable of winning even the biggest of matches.