It was mentioned before but its worth repeating - prob some 3 way design in which one driver handles only the midrange. Sure there may or may not be integration / crossover issues but you can't get a purer midrange than that.
My experience has been quite the contrary. I believe the multiple filter slopes and phase issues involved with a dedicated midrange are of a bigger detriment, especially when the crossover is right at the middle of the mid freqs where our hearing is most sensitive and music is most energetic.
Dollar for dollar, I find that a good 2-way nearly always outperforms a 3-way in the midrange.