I personally would purchase a used pair of Shahinian Diapasons. Like Roy said this is very subjective. Each of the best speakers available have tradeoffs. If you let us know what type of music you listen to and how important imaging, volume levels, deep bass and dynamics are then we can narrow your list. You will get many suggestions on this post. The following names however have repeatedly shown up in the magazines and Audiogon as speakers people love. (I'm sure I left a few out)
In No Particular Order
Vandersteen
Quad
Magneplanar
Wilson Audio
Avantgarde
Shahinian
MBL
Soundlab