Given the pressure of the occasion & quality of the opposition, I thought De Silva's match winning 100 in 96 WC Final at Lahore against McGrath & Warne (that too while chasing, and he came in to bat when SL were at 23-2) was a great knock. It was also the first time that the team chasing won a World Cup final.
His innings of 66 off 44 balls in the SF against India of that same WC was astonishingly beautiful to watch (quality-wise, it was even better than his 100 in the Final).
In the entire 1996 World Cup, De Silva scored 448 runs at an average of around 90, and a strike rate of nearly 110. Back then, they were astonishing numbers. As the best batsman of his side, it was great to watch him perform when his side needed him the most.
Had Viv Richards not played that over confident pull shot off Madan Lal in 1983 WC Final, he would have had a grand World Cup. His innings against Pak in the SF (while chasing) was great knock. I am certain had Viv become out early in that match, rest of the batsmen (no matter how great the names were) would have made heavy weather of it. Viv just had the ability to make difficult, high-pressure situations look so ridiculously easy.