Can't narrow it down to just one so I won't, and I may be showing my age a little with a few of these:
Austin v. McMahon
Austin v. The Rock
Bret Hart v. Jerry Lawler
Undertaker v. Kane, especially their Wrestlemania 15 match.
Razor Ramon v. Jeff Jarrett
Daniel Bryan v. The Authority
The Usos vs. The New Day
