Not sure about the rest of you but I loved the Onslaught storyline in the Xmen in 1996. Turning Professor X bad was just cool. The whole thing. With him recruiting Post, and Holocaust etc.
I wish I had never sold my comics of it. One day I will get them again.
The next Xmen storyline was operation zero tolerance. We could have had Bastian and a better Sentinel army. It could have been awesome.