My favorite Matthäus?
I realized that, for most of ther times, it's the newest one I have listened to, possibly because I tend to discover new things that intrigue me.
So at the moment I'd say the recent Jacobs
I like Jacobs' sense of drama, and I find that the alternation of dramatic and meditative points is quite effective here.
Looking back at my past listening experience, I'd say that Harnoncourt (2nd) and Klemperer are those which I am fonder of, even if now I find the Klemperer one not having a Bach "sound" (sorry, I cannot find a better word) any more.