The best song I've ever heard for MtF voice training is Be Forever Mine, since it helps to bridge low pitches and high pitches.
Unfortunately, the lyrics are not given anywhere, and they're really hard to make out.
Can anyone really good at picking out lyrics please transcribe them?
https://foxamoore.bandcamp.com/track/be-forever-mine
Here's a concert version, which doesn't sound nearly as good, but it's somewhat easier to make out the lyrics: https://www.youtube.com/watch?v=grTDLpOZ8Zc