Having used all of the major tablet OSes, I've decided the only one worth using are the Windows versions. More functionality, less flakiness, and real utility.
I have an HP Stream 7 purchased on sale at the Microsoft Store for $80 (with 1yr sub to Office and no shovelware). I use it for streaming movies (netflix), doing email (gmail and Outlook for work), minor document work, and web browsing. I have simultaneously run Outlook, Word, and a Livemeeting session (participant, not presenter). I've run a VMWare client to manage VMs, iTunes, and other traditionally tablet-unfriendly apps. If I could get my corporate VPN to work (policy issue, not tech), I would use it for my "I want to remain connected but don't need a full laptop" system. Battery life is good.
You couldn't give me an Android-anything. My kids each have one and they're crap (tablets, not the kids). I wouldn't buy a mini-laptop.
Chris