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

It seems whatever speakers I have are the most fun, modifying speakers is my idea of fun. Dahlquist DQ10, mirror image and internal wiring mods. Various models of Alon's, cabinet and driver mods. Merlin VSM-MM, just about every part within BAM and Duelund VSF caps in speaker. Present Klipschorns, every single thing modified with exception of bass portion of cabinet.
I generally keep speakers for many years, by doing mods over relatively long periods of time I create better synergy with partnering equipment. Tuning my system by ear, and for relatively little expense is both great fun and devoid of the audiophile nervosa equipment churning brings me.
And I still have both the Dahlquists and Merlins, can't bring myself to sell them. Dahlquists have been in storage for thirty years, perhaps someday I'll reinstate them. Hearing DQ10's,  Maggies and Dynaco speakers in various high end systems back in the 1970's brought me first awareness of high fidelity.

MartinLogan CLS's, which I still have.  Ok, so you have to learn how to NOT move your head from side to side, even a little, but once you get that down, what a blast.

When I was a young pup, my first "floor standing" speakers were a pair of used Wharfedale W70's with big, 12"+ woofers.  I remember that when the cannons went off at the end of the 1812 Overture, walls shaked and people ran for cover!

Speakers have provided much of my fun in 60 years of audio.  The RTR-6 ESL's were unique; several of us modified them with cork facing to emphasize their dipole character.  They produced the best high end I've ever heard.  They mated well with RTR 180's and 280's (both rather average), but when Bud Fried came out with the H kit, their overall character was more appealing.  Could never mate the 6's with that outstanding Fried transmission line woofer, or any other system, for that matter, but always missed that high end clarity.  Also built Fried's last C-3L's and his matching subwoofers (SM-3's), a system that can still "disappear."  Just now finishing Linkwitz's LX-521's, a project that takes some dedication.  Amen to those who mentioned Bob Fulton, a real gentleman and interestingly oblique thinker, as exemplified by his J's.  Still have a number of his fine recordings of amateur groups.   

kenjit again (another forum he started 12-29) states he has superior hearing and cables are all the same. Wrong again.

Speakers which I shouldn’t have sold are Acoustat 2&2s over 30 years ago. I owned them back when I had inferior equipment, cabling, room acoustics and no tweaks. I bet they would give my Legacy Focus a run for the money in many ways using my high end system. Looking to replace the Focus speakers when I can afford to match my system & room (for Von Schweikerts).