What's the best and/or favorite piece of equipment you've owned? And do you still own it?

I love my Ocellia Calliope.21 Broadband loudspeakers. Both how they look and how they sound. If you don’t know these you can check em out right here https://youtu.be/4avuiiF3I2g

ATC SCM 40 v2's 
Amazing sound for their price range.
Built like a tank.
Will never part with them 😎

I still long for my Philips 212 turntable with the green elevator buttons. However, it is the Naim Superuniti that has given me the most
music and versatility. It now runs through a Primaluna HP amplifier that has added
the missing tone and fullness that the Naim
lacked. Pushing a pair of Focal Kanta 2 speakers. This rig will keep me happy for a long while. 

Antique Sound Labs Wave 8, the only item (I own) going for more than when they were new. 

My 15 year old UK made Castle Richmond 3i small standmounts. Recently dug 'em out for a change from my Quad S2s and they ain't going back anytime soon.