The best Android tablet is the Android tablet that can run Android 3.0 'Honeycomb'. And I guess that means the Nook Color, which has just received a port of Android 3.0 Honeycomb. Which you can install. Right now. Well, if you have a Nook colour, that is.
Based on the Honeycomb SDK preview, the port isn't all the way there yet (sound doesn't work) but it'll give you a good glimpse of what Google will show off tomorrow at their Honeycomb event.
Here's what does work in the Android 3.0 port:
-Graphics acceleration -Accelerometer -Wireless! -Touchscreen -Buttons -Sleep/Wakeup