I use the Harmonicdog MultiTrack DAW. From a professional audio engineer's point I'd say the app is pretty much amazing. I've recorded ideas up to 8 tracks long so far without a hitch. You can listen through the headphones to whatever you choose to monitor while you do over dubs, punch in and out, adjust stereo imaging, levels it's pretty much the neatest thing I've ever had for on the go. As far as beat making goes I don't think it has a whole lot of to offer in that field, mainly for music production and recording real instruments live. Nano studio hands down.

1. Incredibox
2. Best Free Beat Making

Incredibox

Best Free Beat Making

I have it and have made a bunch of songs on it. Python installation for mac. I would honestly say its more advanced than Garage Band software wise, which is saying alot considering its a phone app. The only thing its missing are instruments other than synths. There are over 100 preset intruments but they are all synths, and none are guitars or other instruments. Also, you can only have 4 instruments and 2 drum tracks going on for one song. If you want a 5th instrument, too bad. But I would say those are the only negative things about it.