Well. If you're looking for the most straight-forward solution, you can't go wrong with CocoonJS' cloud service, the Intel Appmobi XDK or Phonegap Build.
My personal favourite is Phonegap Build, which doesn't even require any additional software. Just sign-up with them or sign-in with an existing Github account, upload a zipped folder with all your files and press "Build".
Supported platforms: Android, iOS, WebOS, Bada, BlackberryOS 5/6/7, Symbian and Windows Phone 7.
In addition to the aforementioned platforms, the regular (offline) Phonegap also supports Tizen and Windows Phone 8, but requires quite a bit more work.
As for suitable devices: it very much depends on what OS you want to implement with and how much money you can spend.
For Android, I'd suggest either the Google/Asus Nexus 7 (powered by the purest Android Jellybean) or an Amazon Kindle Fire HD/Nook (both quite affordable).