Where is "Voice" on New Projects in GarageBand now?
They have taken that option out of the new project area in the latest version. You can use "Songwriter" and delete the drums and guitars, or chose "Empty Project" and add a vocal track.

If you want to get the settings you've used before you can open an old project and use "Save As..." after deleting all the audio (not tracks) to get a blank project with the settings you like.