I say this to a lot of people in regards to this question and my short answer is logic. Reason I say is because if you are buying a mac, you get a program called GarageBand already installed. That's the baby version of logic. You can use that to get your head around the basics or audio, midi, mixing, structuring etc. Once you're familiar with the functions of GarageBand, logic is the next step. You jump straight into it and you only really learn a few little things that GarageBand doesn't have. Layouts and functionality are very similar