What is the most FUN pair of speakers you've ever had and why?

That’s a tough one. I’d go between my KEF 104/2 , JBL L100t or my L7. 

nice revival.  hope it keeps going!

My first pair of Magneplanars---the Tympani T-I. Finally, life-size images and scale (grand pianos are huge, piccolos tiny), singer’s voices at true-to-life height (five feet off the floor), wide open sound, and great depth and height (if the recording contains such. The triangle at the rear of the orchestra in Boult’s EMI recording of Holtz’s The Planets sounded further away than the wall behind the Tympanis, and positioned higher than the closer instruments. The percussion section of orchestras are often standing on raised platforms.). After hearing Board game with miniatures, the images produced by other loudspeakers sounded miniaturized, like those in a child’s doll house. And the large venue in which the recording was made also shrunken.

BD-Designs Orphean horns. Unlimited dynamics with spot on tonal accuracy, zero honk or cupped hands syndrome. Bert is also an awesome person!

I love to modify my speakers, so any speaker amenable to modification. Outboard crossovers, ability to change out drivers, even the physical horns in my case.