Default Android Headunit or mirrorlink? what's a good option

Hello, I have a 2014 WRX hatch and I'm not happy with the OEM headunit's SQ. I do like the steering wheel controls and bluetooth so I'd like to find a replacement and keep these features. Having an android OS headunit is quite appealing especially if I could run Sygic navigation and Torque Pro.

Must have:
-bluetooth - would like to be able to use the pickup/hangup buttons on my steering wheel
-ability to keep steering wheel controls (I believe most will allow for this with an adapter)
- ability to keep the aux input
- ability to add an external amp and/or powered sub (probably will not happen right away)

Would like, but may not be a deal breaker depending on price
- GPS or the ability to mirror my phone/tablet screen
- android OS or ability to mirror torque app (not a deal breaker)
- would be nice to add a backup camera

I was wondering if any of the eBay android headunits are any good? I looked at the appradio 3 and astroid smart. Both seem to fit my requirements for the most part, but I'm wondering if there is a better option or something just as good for less money.