What's the best mid-range driver available?

ATC makes the finest midrange driver in the world, as Soix said. i know there is as least one site that sells them to the public, through ATC.

Dunlavy V's have Domes by Vifa they sound excellent to me.

*ATC WORLD CLASS* END OF STORY !!!!!!!!!!!!

Here is a link for the spec's on the ATC
http://web.archive.org/web/20010411204809/www.atc.gb.net/sm75-150.htm

ALE drivers from Japan are cost-no-object products. Their 7550DE lower midrange and 4550DE upper midrange compression drivers are approx. $2,500 each without horn. Their 1260 upper bass/lower midrange driver is $10,000 each. Adding an appropriate Tractrix horn (Sierra Brooks) could add another $2k each.

TAD's 4001 compression driver retails for $1,666 each and is no slouch either.

Both of these make the ATC look/feel like a small toy.