I agree with
@Howie, most rides are better at night (perhaps a better topic would be "rides that are better during the day").
But, in the spirit of the question - there are four that spring to mind for me. Rides that had truly defining night rides for me.
Steel Vengeance - this is obviously a top 5 ride during the day, but that might ride is what makes it number one for me. The fact that
@Snoo and I (after he'd had over a dozen rides and I'd had three) both completely mistakenly thought the track was turning right, not left, during one of the final overbanks basically says it all. That ride is just something else.
Lightning Rod - another one that I'm thankful to share with other CFers, but that night ride hitting the crest of that second hill in, what can only be described as, "complete darkness" then racing down the quad-down towards the lights of the park, was yeah... special.
Beast - see all previous topics and posts.
Taron - this ride benefits from two things in the evening/night. One, the fact the ride has warmed up so much. Two, Klugheim at night. That's all I need to say on the matter really.
Honourable mention to Helix, Boulder Dash, Fury 325, Voyage or basically anything else in my Top 20.