If you were a DJ, what song would you end every set with, no matter what?

I'd end any and every set with Brian Eno's Spirits Drifting. I'm not writerly enough to explain why. I just love the atmosphere. Eerie and lovely.

Skeeter Davis - The End of The World

The DJ at the terrible Ritzy's nightclub I used to go to as a student would end each set with Simply Red's version of 'Every Time We Say Goodbye'.
https://www.youtube.com/watch?v=teH5as8Psng

Pink - Get the Party Started

ffs, yet another reason to semi-irrationally hate Mick Hucknall
https://www.youtube.com/watch?v=l8RHCC5V5Bk

My co-DJs at the gothy industrial wave night I would play at always ended the night with 'Goodbye Horses'. Worked v well.

That’s such a great track to close a set

'Goodbye Horses' always a good shout.

This too -

https://www.youtube.com/watch?v=FXjUWtLwxLk

Ha, I used to finish with that Cristina track in the late 80s, the other one being “Cloud Chamber” from David Byrne’s Catherine Wheel soundtrack.

https://www.youtube.com/watch?v=uBTIydRB2Pg

Haha I used to finish with the Cristina track at my new wave / post disco night too. Thought I was being an original! My trick would be to keep slowing it down and down until it came to a sickening crunch at the end

Not quite answering the question but I saw DJ Justin Robertson smash up Glasgow’s The Arches in the mid 90 with 2 hours of hard house, only to finish with Massive Attack’s Hymn of the Big Wheel. Lovely!