The only reason why you would buy a tablet is for mobile media consumption (videos, music, internet browsing) on a larger screen than a Smartphone.

Productivity on Tablets is still not as effective as an entire computer.

Anyway, the best tablet out right now is the ASUS EeePad transformer, cheapest Tegra 2 tablet with Rock Solid and Heart Touching(lol) ASUS build quality. For about $399 you have the best specifications and build quality. The Transformer Dock also makes it a netbook! :O