All-Star Baseball 99
ASB '99 is easily one of the best baseball games to come around in quite some time.
World Cup 98
On the basis of AI improvements alone, World Cup 98 is highly recommended.
FIFA: Road to World Cup 98
This is a great conversion of the 16- and 32-bit franchise of the same name.
It's cartoonish arcade action, filled with impossible dunks and special-power-up rewards.