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

Back in the mid-70s I had a set of double Advents, stacked vertically, on custom stands, tweeters together. Powered by an HK Citation 16 and Soundcraftsman preamp with octave EQ, Thorens TD-160 and an Ortofon MC cart. It combined the Advents neutrality and bass, doubled up for the wall of sound bigness and the dynamics of a whole bunch of power, with the kinda peaky Ortofon making up for the Advents soft upper treble.  That system rocked. With 4X10" woofers it could play the subterranean synth bassline on Stevie Wonder's "I Believe (When I Fall In Love)" from Talking Book like few others. The Eagles "Hotel California", Linda Ronstadt, they all sounded fabulous, as did Keith Jarrett's "Koln Concerts" Al di Meola "Mediterranean Sundance". 

While I’m in love while in in love w my Energy RC-70s’ currently, they sound amazing.

 My most fun pair (which I still own)

CERWIN VEGA D9s’—- Great sound and thump.

 Honorable mention - CERWIN VEGA AT-15s’- a more crunchier midrange than the D9s’, but less bass.
 For a few years I had both pairs stacked w D9s’ on bottom and AT-15s’ upside down on top. That was some of the best music I’ve ever heard,, I eventually ended up melting the binding posts on the back of my Onkyo m-504 amp.
 Have since learned about the work OHM LOAD,...and why it’s IMPORTANT when choosing an amplifier for driving an amp at a basically 0 ohm load.

:))

I enjoy my Pique restored Quad 57s and 63s. Also loved my DQ 10s for a number of decades.

RCA Photophone horn system ran a pair for 10 years sold them but bought another since I missed them so. 

The used pair of 1977 Klipsch Cornwall I systems were utilized for program material playback. Also, these were utilized with "live" performance of electronic keyboard performances. Efficiency and moderate performance linearity were the reasons for "fun" value.