Warn Sound Capacitor

ClarityCap PX are really nice for the money.  Neutral to warm, it is an excellent sounding cap that won't kill you in price.  Higher end ClarityCaps are really flat in frequency response.  If you want to spend a pit more, I would look at Mundorf.  

Both are available at Madisound.  

This is a review of a LOT of different caps with sound presentation of each.  

http://www.humblehomemadehifi.com/Cap.html

Haven't heard ESA.  PX is definitely warmer than CSA.  I use both in different speakers and the CSAs are very neutral.