I personally think that the rivalry between The Rock and Triple H is sometimes under appreciated when compared to the likes of: Austin/McMahon, Undertaker/Kane, Triple H/HBK, etc...
Throughout the first half of 2000 these 2 were the main attraction and had a succession of 4 PPV main events (WM 16, Backlash, Judgement Day, and KOTR). At this time Raw and Smackdown were both equally fantastic at furthering their hatred. I still remember the Raw after JD when The Rock stalked and assaulted every member of the McMahon-Helmsley faction, it made for great entertainment.
For me though, Backlash 2000 was they're greatest match. It was the rematch after The Rock was screwed at WM 16 by Vince who had aligned himself with the faction and it also featured the return of Stone Cold. Some will agree that The Rock was much better chasing the belt as opposed to carrying it for any length of time and a good part of their rivalry was the chase. The Rock was red hot and Triple H was the best and most hated heel in the company at that point, these 2 had grown so much since they're last proper feud in 1998 (I'm aware of the brief feud in 1999 but it was only for a short while and was more about Triple H moving into the title picture with Austin).
The build for the match was great, the video promo at the start of the PPV and the promo before the match are still 2 of my favourite promos to this day. The uncertainty of Austin showing up and whose side he would be on, this provided a lot of buzz to the match.
The match itself is a fantastic medium paced classic wrestling match between the 2 who knew each other so well, there's not one missed step that I can see and every move/reversal is executed perfectly. It also includes the now legendary double Rock Bottom through the announce table with Shane McMahon. Inevitably McMahon and his stooges get involved and try to screw The Rock again but are met with a chair wielding Austin who cleans house and makes way for Linda McMahon and Earl Hebner who then counts the 3 for The Rock. The crowd was amazing and were into it the whole way and went nuts both when The Rock won and when Austin returned.
It might not be the hour long epic of their Iron Man match (The best part for me is The Undertakers return, that still gives me goosebumps to this day!) but I will always enjoy this match and I still maintain that Backlash 2000 was the finest PPV of that year.