I love those two events, they are my absolute favourite events in comics, but I didnt expect anyone else to agree.
I love them both.Especially Final Crisis.
I'll go with No Man's Land because I can tolerate small events that affect only one group of related characters like the Bat-family or the Green Lanterns but I can't get into big events that involve the entire comic universe. I just feel bogged down when there are too many characters involved in a story especially if the amount I am invested in reading about are outnumbered by the amount I don't care for.
No Brightest Day? And I'm surprised how many people chose Flashpoint :/
For me it was close but I chose Infinite Crisis. Something about it, its art, its at-the-time mindbending crossovers, it'd have to be one of my favourite stories of all time.
Crisis on Infinite Earths has Perez drawing every DC character and had a story that blew my mind.
If I had to more votes, I'd vote for Sinestro Corps War and Blackest Night (but minus the tie-ins that aren't issues of Green Lantern or Green Lantern Corps).