Best Multiplatform App Support?

[cheinen]

I've been doing my research for a new NAS solution based on the following requirements:

1. Day-1 storage requirements are for ~1TB of Data
2. By Year-3 storage is expected to be ~4TB, growth is expected to be about straight-line(1TB/year).
3. Data types will be pictures, video, music, an iSCSI carve-out, and some generic file sharing.
4. Strong Support for iOS and Android (and other app support) is VERY high on requirements list for playback and remote/cloud access.
5. Looking to support access from a multitude of devices: Windows PC, iOS, OS-X, Andriod tablet, Roku, Squeezebox, and cloud/internet/remote.
6. Performance requirements are somewhat modest ~50MByte/sec.
7. Day-1 Budget is just about $700-ish, including drives, and final budget is about $1600-ish. I could spend it all today, but I'd prefer to stretch it out.
8. Backups of critical data will be done to Livedrive (probably via PC).

I think that pushes me towards either:
QNAP 239 Pro II+
Synology DS-712+
Netgear ReadyNAS Ultra4

What I'm hung up on is that after capacity, application support is my biggest driver for this.
I'll work with whatever back-end complexity is needed for setup/admin, but I need a smooth shrink-wrapped experience for my end-users.

I've tried to read the app reviews in Google Play, and iTunes App store, but it all looks pretty balanced.

Anyone have advice about how to rank these companies for mobile applications?
(who's innovating the fastest, who's the got the most idiot-proof interface? who is out-right just the best?)

Thanks for any help!