I was at both the 98 and 99 Olympias, my wife was an exec for NBTY at the time and got primo tickets for every major show. I think 99 was his best showing, he looked unbelievable. In person he was inhuman, Can't put into words how much muscle he carried, I felt puny next to him.
As far as who was better, him or Dorian....Iv'e only seen Dorian in person once at Bev's gym and he was covered up.....but he looked thicker than a Rhinocerous, his forearms looked like hams they were so thick. They are the number 1 and 1A BBers of all time.....depends on your personal preference.
The fact that Yates defeated Ronnie before he was RONNIE means nothing....a lot of guys beat him that he then dominated for years