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

My favorite is a pair of horn-loaded 3-way speakers from the 1960s that were my Dads. University "Dean". They are huge and heavy and super-efficient (103 dB at 1 watt at 1 m). I have them at a vacation home and am always blown away by how great they sound. Big live, natural sound. You can feel the air movement when they are cranked. This system rivals my main system that costs 15 times as much. Unfortunately, I will have to sell them soon as we are downsizing, let me know if you are interested.

My biggest regret was selling a Sansui  777 integrated amplifier back in college. I have yet to see another one. 

Woodsong Garrard 301 wt Triplaner arm and Miyajima Shalabi cartridge. The beauty of it and the function always thrill me. Not to mention its drive and impact. Never had another TT that recreated music with such reality. And I just love to look at it doing its thing!

15 year old Magnepan 20.1s, originally $12,500, bought for $5,500 right here on Audiogon. Magnificent sound.

Mac 2105. Still have it after 44 years.

Conrad Johnson Premier 7A amplifier.
That was an absolutely transformational piece for my system.
Followed by Thiel CS 2.2 speakers.
With the Connie J I probably didn't get the low end grunt which the 2.2's were capable of. But the mids, high end and imaging were positively heavenly.