Windows Phone looks like something I'd like to give a try, especially given the spotty experience I've had with Android so far. And if I were to get a tablet, I'd definitely look into a Surface Pro (once they aren't so expensive).
Perhaps I'm less of an Anything-But-Microsoft guy than most around here.
There's a growing number of cheap 8-inch Windows 8 tablets like the Dell Venue Pro. Only 32-bit and 2GB of RAM but they work well as tablets and you can use them with Bluetooth keyboards. They run desktop software but screen elements are really small so you may want to add a couple of big monitors for more serious uses. The Asus Transformer T100 is also worth a look.
I absolutely love the Venue 8 Pro I received from my wife for Christmas. It is quite remarkable and liberating to have a full PC in such a tiny form factor. Put simply, it can do anything my desktop PC can aside from display dozens of windows simultaneously. And of course it's not as fast as my 3770K. But it's shockingly fast for such a small device thanks to Bay Trail. And Windows 8.1 does the "tablet" thing really well at that size.
Perhaps I'm less of an Anything-But-Microsoft guy than most around here.