Hogan/Vince was the big match of the show. After that I'm not sure what the actual order was, but I believe it was:
Not sure though. That's what always struck me as far as match order in importance went. Maybe 2 and 3 are switched.
Hogan/Vince was by far the most promoted. In the week before the show, the main event slot changed every day between Rock/Austin, Angle/Lesnar and Hogan/Vince. In a Roundtable a year ago, JR said that Rock/Austin was supposed to close the show but with Austin's condition the night before, they thought it will be safer to deliver in the main event with Lesnar and Angle, crazy weekend with all the drama.
As for biggest in promotion:
3. Angle/Lesnar - for this match, everybody knew that we're getting Angle vs Lesnar in the main event of WM19 from August of 2002, that was THE match for the background of the athletes alone. Combined with all the talk about their real mat wrestling contest in 2001(which Angle won BTW)and Angle's ON/OFF status for the match, they had a lot of hype.
4. HBK/Y2J above Booker/HHH because they started this with a teaser in December 2002, a great 4 months program while Booker just got his match on a battle royal after NWO(+ the stupid race angle they did with HHH).
This is Top 3 PPV of all time IMO, WM17, WM19 and Summerslam 2002.