In my mind the undisputed God of Bach keyboard playing is Glenn Gould.  The wildly famous Goldberg Variations recording is a good introduction to the world of Gould's Bach.  There are two versions of this available, one which is his debut recording (1955), and one he recorded right before his death (1981).  I prefer the later one because he has a broader understanding of the variations as a whole.  However, both recordings are great, and eventually you should really have both.
    Moving on from there, why not pick up Gould's rendition of the Well-Tempered Clavier, book. I?  Once you hear that you'll want book II as well.  There is a great double-disc set of keyboard concertos that can ease you on your way into Bach's ensemble work.  On the non-Gould side of things, there is a great recording on the Philips label of Bach's "Musical Offering".  This is a must-have for anyone wishing to get to know the music of good ol' Johnny Bach.  I could go on and on and on and on....and I will if you mail me asking for more recordings.