My own choice of music for coin-operated pianos is ragtime, early
Broadway show music (songs from the "Follies", "Passing Shows", et al),
early blues, marches and one-steps.

Due to the paper drives of WW1, most of the surviving rolls for
coin-ops are 1920s vintage, which I feel have been overplayed and are
actually representing the declining years of the industry.  Ragtime,
America's first original music, in fact, grew up with the coin piano
industry in this country.  I believe that the coin piano, orchestrion,
band organ, photoplayer, etc., helped to spread ragtime music's
popularity and prominence.

I would have to say I prefer the so-called "straight" arrangements of
Wurlitzer to the interpretive arrangements of, say, Automatic or Clark.
And everybody falls in love with Link arrangements (arranged by Ray Deo),
early Peerless (also arranged by a great concert band arranger, C. W. 
Wheeler), and of course the mighty O roll (arranged by P. M. Keast).

The best thing to do is listen to as many instruments as possible and
develop your own likes and dislikes, and try to get a copy of Reblitz's
master work, "Treasures of Mechanical Music", to read about the
arrangers and various music scales.  Have fun!

S.K. Goodman