The trio of Android tablets — the Nexus 7, Note 8.0, and Venue 7 — tie as your second-best bet for doing work from a media tablet. Their Android 4.2/4.3 Jelly Bean OS has solid security capabilities and Exchange support, their Email and Calendar apps are solid if unexceptional, and both Mobile Systems' OfficeSuite Pro and Google's Quickoffice HD Pro apps for Android are capable enough for most business work. Plus, as with the iPad Mini, you'll find apps for a wide variety of business needs, from Salesforce.com to SAP access. As with the iPad, any compatible apps you purchased for other Android tablets can be downloaded at no charge to your Nexus 7, Note 8.0, or Venue 7.
The Note 8.0 has a larger screen, which helps readability, and Samsung has tweaked several mainstay apps such as Calendar and Email for easier usage on its less-than-full-size screen. Plus, its included S-Pen digital stylus can make note-taking and other activities easier than on other tablets.
The Kindle Fire HDX supports Exchange, including the same kinds of security policies as standard Android devices. The Email and Calendar apps have simpler UIs than the stock Android versions, to fit better on the small screen. But all the capabilities you need are there, including attachment previews and calendar invites. I was impressed with their quality, given the Kindle Fire HDX's decidedly nonbusiness target user. It too can be used in a pinch — if your business is willing to let it in.
Although the Amazon Appstore is curated, the Kindle Fire HDX allows sideloading of apps like other Android devices do, so you can install non-app-store apps. Google's Quickoffice is no longer available for Amazon's Fire OS, so you're stuck with a limited selection of mainly unsatisfying office apps on the Kindle.
You can buy the Windows 7-based version of Microsoft Office for the Venue 8 Pro, but it's unusable on a tablet's small screen. There are no decent productivity apps for the Metro user interface in Windows 8. But there is a decent email app in Windows 8.1: the Mail app in the Metro UI. Just note that it does not support POP accounts, such as those typically provided by Internet service providers. The Microsoft Store for Metro apps is curated, but you can install any "legacy" Windows 7 app via its installer file, so malware can make its way in.
The business connectivity winner. In all cases, assuming you're permitted Exchange access from your media tablet, you have basic email, calendar, and contacts capabilities available. But to do real work routinely, your best option is the iPad Mini, followed by the Android tablets. Windows tablets simply don't have usable business software, and neither does the Kindle Fire HDX.
Sign up for CIO Asia eNewsletters.