I don't know why your criteria leaves out Biggio's early career. I don't accept that frame of the discussion.
1988 negligible
1989 Biggio - Silver Slugger catcher
1990 Biggio - solid catcher with speed
1991 Biggio - All-Star catcher (Bernie a part-time rookie)
1992 Biggio - All-Star 2B (Bernie still part-time)
1993 Biggio - even more pop (Bernie full season, league average)
1994 Biggio - AS, GG, SS 2B (Bernie above average CF)
1995 Biggio - AS, GG, SS 2B (Bernie above average CF)
1996 Bernie - adds more pop (Biggio slightly down year, still AS, GG)
1997 Biggio - first really close year, both AS & GG, comparable OPS+, slight edge for Biggio, but contestable
1998 Bernie - another big year for Biggio, but even bigger for Bernie
1999 Bernie - AS, GG (Biggio takes a step back)
2000 Bernie
2001 Bernie
2002 Bernie - three big years for Bernie, Biggio is only average
2003 Biggio - almost identical seasons, except Bernie missed a big chunk
2004 Biggio - another similar average offensive season for both, Bernie now moved to DH for part of the season
2005 Biggio - Bernie fading, Biggio still solid and back at 2B
2006 Biggio - still has power, but both are mediocre at this point
2007 neither - Bernie done, Biggio a liability
There are some arguable years, but I've got 12-6 in favor of Biggio.