TBH, chap, I'd steer well clear of Pro Tools. You're using a Mac; get Logic Pro! Garage Band is the 'most basic basic' recording option that Apple offers (hence the free nature when you buy a machine!). It is, however, still a perfectly viable scratch pad for ideas when you're on the go! The instruments that are built in are quite nice; some of the synths are really bloody good. Also, they can be accesed in Logic & Logic Pro.
Reason. I've never tried to use Reason with Pro Tools (in all honesty, I've never really bothered with PT. Tried to use it for a couple of projects during Uni and never got to grips with it, so moved straight back to Logic! God, that was a long tangent...) but I know that it run seamlessly with Logic Pro. I use a *ehem* cracked copy at the moment, primarily for the ReDrum and Malstrom, and they sync up quite happiy via ReWire - the looping doesn't work quite so well, but overall it does work just lovely; I'm sure a legit copy would work 101%.
I would seriously consider a copy of Logic Pro. It's £500+, but you get EVERYTHING that you can do with Reason, Garage Band (you can import GB project files in), and Pro Tools. All of the Core Audio instruments are fabulous; there's even a ReDrum-style drum machine!
Check it -
Logic Pro