UFC 12 was pretty good. Vitor Belfort's debut against Telligman and Ferrozzo and the crowning of the inaugural HW champion with Coleman vs Severn. Plus the scrap that was Yoshiki Takahashi vs Wallid Ismael.
I think the tournaments were the best. UFC 2,4,6 and ultimate ultimate 96 were the ones that stood out. Ufc 12 was good with vitor. 17 has pete williams v coleman that was really good + tank/duarte 22 Frank shamrock v Tito was the best ufc fight up to that point and I remember ufc brazil being good. Also ufc 31 was just when zuffa took over but still one of my favourite events
UFC 17 without a doubt. The tournament fights are all great culminating in the epic Henderson/Newton final. Chuck Liddell debuts. Tank squashes Hugo Duarte. Mark Coleman gets upset by Pete Williams. Frank Shamrock does battle with Jeremy Horn. Phenomenal event.