I have the Kindle Fire HD and love it! I haven't used any other tablet so I can't compare, but I like the size and the resolution and sound is amazing. I have been watching Game of Thrones on it and it is pretty darn awesome. That said, there are a few features I don't like about it. The user interface, while decent, isn't quite as intuitive as Apple products. Having both the Powerbook and the iMac, I do love how easy Apple products are to navigate. But, you are paying over $250!
Curious about the Google Nexus 7.