I think all of the major recruiting sites have databases going back at least 10 years
I like to use the
RSCI rankings, because they rank them based on the average of multiple services . . . and, it's free. Their database goes back to 1998.
going back a little further, here are PrepStars #1s going back to 1990:
1990 Shawn Bradley, BYU
1991 Chris Webber, Michigan
1992 Othella Harrington, Georgetown
1993 Jerry Stackhouse, UNC
1994 Felipe Lopez, St. John's
1995 Kevin Garnett, NBA (#2 was Ron Mercer, Kentucky)
1996 Kobe Bryant, NBA (#2 Tim Thomas, Villanova)
1997 Tracy McGrady, NBA (#2 Lamar Odom, Rhode Island)