There's been a lot. But when you think of the moments which have had the most impact, which three do you think are the most important moments in the X-Men?

That's really a hard choice.

What do you think ?

Probably:

Storm, Wolverine, Nightcrawler, etc.... joining the X-Men

Xorn's attack on New York and killing Jean- (It ushered in the Emma/Scott regime)

AvX- End of the last Era of X-Men

Maybe, some people would pick the days of future past or the Dark Phoenix Saga. Death of Jean by Xorn really did change things for X-Men comics, change for the worst.

I guess just off the top of my head I'd say the whole dark phoenix thing, the fall of the mutants story was pretty big, as was days of future past. House of M and Schism as well though the events werent necessarily great but in terms of importance. House of M in my opinion really changed the focus of the xmen. Though oldnightcrawler has kind of convinced me that M-day really wasnt a huge tragedy in terms genocide and lost of life. Right now I cant think of anymore maybe I might have to break it down in terms of 3 biggest moments every decade since there really are quite a few.

"Hear me, X-Men! No longer am i the women you knew! I am fire! And life incarnate! Now and forever--I am PHOENIX!"

/thread.

This is interesting, since Fall of Mutants was kind of 3 big stories in its self...but i guess it depends on how you see it.

Maybe, but it definetly ,made the comics move forward and forced the writers to play with the newer X-Men themes.

That's true, it looks like Cyclops and Wolverine have been only characters who have benefited from Jean absence, that's debatable at best. Emma Frost benefited from Jean absence in the early 2000's to mid 2000's, but not in the late 2000's.