I can see some features being different between the platforms. I'd guess that iOS probably has more bells & whistles, based on the functionality of their libraries. On negative on iOS is that libraries get deprecated pretty quickly, forcing you to keep updating the app and the OS. In my last job, we had an iOS kiosk app to go dark, simply because we'd failed to update it before the app certificate expired. I'm pretty sure that Android doesn't force as many OS and product updates as Apple does so, if my iPad mini truly can't be used, I'm likely going to get a Kindle Fire. Only thing I hate about Kindle is the ads but I believe you can turn those off for $15.The differences appear to be outside the main features (list as of today):
iOS only - MIDI, gyro positioning of movers, Ableton Link, Custom dial (allow for dial to control iris size or speed of roller barrel)
Android only - direct powering dongle via USB, direct connection to dongle via USB
So, if you don't have a tablet, I would recommend an iPad. If you have one, or prefer Android, doesn't seem like you give up much.