Hmmm, I've not owned many pairs and I've enjoyed them all.
Memorex S20s (we all have to start somewhere!)
Tannoy Mercury 5 Golds
Cyrus 780s, the d'appolito ones
Mission 700Es
Mission 702Es
Alesis M1 mark 2 actives, surprisingly good hi-fi speakers actually!
Martin Logan Aeons
Revel Performa M22s
Musical Fidelity MC1s (modded)
Elac CL310i Jets
I quite like them all, the Revels were easily the best though, even better than the Martin Logans which are way too fussy about music type, placement and room condition. Still, the MLs are very very special if you get them spot on.
The Elacs are truly special, a very open window and completely neutral in every way.

