FL Studio (when the computer is working).
Strictly speaking, I don't need all of it's capabilities but it is a fantastic program. Audacity would be adequate for audio books but FL gives me the ability to easily create electronic scores, using the powerful piano roll with no musical knowledge. I have tons of effects and mastering tools all in one handy package and with it's life time free updates, it was well worth the money. Something I can grow into, as I learn more about music creation. So far, it's been ideal for creating background music and atmospheres (weather, creaky doors, industrial soundscapes, etc) for my plays.