I believe Manchester encoding was used in magnetic media back in the stone age when I designed hard drive and floppy drive controllers (before chips did it).

I believe one of the advantages was that the encoding process did a better job of equally distributing the magnetic transitions, which meant they were less likely to push apart when the transition densities increased on the media. This property could be advantageous in other applications.

I'd like to hear within which applications its used today.

-Jay C. Box (Codeasaurus Rex)