I was about ten when he played at Old Trafford, so I'm maybe over remembering his performance, but I remember him rag dolling the defence all game, never giving the ball away and then smashing it in every time he shot. Not many folk scored hat tricks at Old Trafford. I'm fairly sure it was the 2002 WC that he ran riot in too.
But aye, he was clearly on the decline by then, looking back. I like Messi and all, and it's enjoyable seeing him dance through eleven folk, but if you watch Ronaldo at Barca you get all that plus this explosive power. I'm always going to be biased towards him.