Both C#m and Db can be played on piano using only the black keys (skipping the 3rd note of the scale). This makes them easy keys for beginners. I'm not sure if that's the reason, but it could be related.

Anecdotally, I know a few vocalists that sound great in these keys and use them as a starting point

> Both C#m and Db can be played on piano using only the black keys (skipping the 3rd note of the scale)

For the major scale, there are 7 notes in the scale and only 5 black keys; you also need to skip ti, the 7th note.

For the minor scale ("C#m"), it's worse; only four of the five black keys are part of that scale.

And I would have thought that something intended to be played only on the black keys would be described as using a pentatonic scale anyway?

As a belated followup, I should observe that if you're playing "in C sharp minor" on the black keys, you're skipping notes 3, 6, and 7 of the scale... and those are the only notes that differ between a minor scale and a major scale, making the "minor" designation completely meaningless.

Electronic dance music is the biggest genre in the data. So then easy to play shouldn't matter. It's still an interesting question. I think playing Db is pretty nice on the piano even if it's not the easiest.

There is a sweet spot for the bass. Lower is better for deep bass, but too low and it stops being a recognizable note, and consumer speakers can't reproduce it. This effect exists though I'm not sure if it is the cause of the pattern here.

Difficult to play in what instrument?

C# I don’t believe was/is a common tuning for most western instruments, classical or modern.

A digital piano can transpose things to make it “easier” to play.

Cursory google search says that a sitar is traditionally tuned to something useful for c#

I’m curious if C# is one of those notes that lines up nicely with whatever crappy consumer stereos/subs were capable of reasonable reproducing in the 90s as electronic music was taking off and it stuck around as a tribal knowledge for getting more “oomph” out of your tracks.

I play piano and don’t mind playing in Db at all. The chords fit nicely in the hands

i believe the most popular reason is capo on 1st fret when writing songs, other factors coming 2nd or 3rd (electronic music, sped up old samples, etc)

For electronic music, it's around the lowest bass root note that most systems can play well without a subwoofer. C pretty much requires a sub and things rarely go lower than that.