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

Tice clock. Vpi magic brick. 
Seriously, As  smandlej above, Michell Gyrodec Full Plinth, SME V arm, remove the bridge, full Gert Pedersen mod takes it to another level. 

Original Audio Research D-150.

Wish I still had it!

Cheers!

I don't think I will ever part with my Emotive Audio Epifania preamp and Vita amps. I have owned them for over 15 years now (serial #2). Over the years some changes have been made. The original caps have been replaced with VH Audio copper teflon caps (preamp and amps). The preamp's original volume control was replaced with an autoformer volume control, and the plate voltage on the amps was increased to properly run 6550 tubes (originally used 6L6 tubes).
I've changed speakers a few times and am currently using Bache Audio Tribeca's. 

My first decent speakers age 19, were AR2x. I was ransacked years later, took me a lot of years to get over the loss of those speakers.