Here is the last of the 1990's sets (Bowman, Donruss, Fleer, Score, Topps, Upper Deck) I'm going to profile. Check Capewood's Theory of Baseball Card Evolution.
Although Score did it first, putting a color photo on the back of the card in 1988, Upper Deck did it better in 1989. 1989 Upper Deck was printed on nicer card stock, had a full card length photo on the back and a holographic logo on the back to prevent counterfeiting. It was also packaged in a foil wrapper to prevent pack searching. And they had the luck to include Ken Griffey, Jr.
1990 Upper Deck #532 Edgar Martinez
1991 Upper Deck #132 Ryne Sandberg
1992 Upper Deck #125 Eric Davis
1993 Upper Deck #364 Travis Fryman
1994 Upper Deck #112 Wade Boggs
1995 Upper Deck #142 Fernando Valenzuela
1996 Upper Deck #85 Derek Bell
1997 Upper Deck #48 Lee Smith
1998 Upper Deck #224 Dennis Martinez
1999 Upper Deck #52 Nomar Garciaparra