I personally prefer one who will differentiate between the two. I'm well aware where the lines are between them, and I believe most buyers who do differentiate, place that line between the pentium 3 slots, and the pentium 4 sockets.
As far as AMD sockets, etc., you'll need another definitive point of reference, because I really can't tell you there. You might find a clue by studying their respective CPU pricing, and looking for which type CPUs have the enormous price drop?