Mark Dain I need to start composing music. I love listening to instrumentals, it seems like the only way to express emotion when words won't quite cut it

Asko FL Studio all the way. It's expensive, but a full-fledged music production software used by names like Martin Garrix, Avicii, Madeon, BT, Deadmau5, Boi-1da and so forth (image-line.com/fls...), and also what I use.

Mark Dain Know anything that runs on OS X? GarageBand looks a bit limited