What's your favorite screen size?

With all the different sizes of gadgets out there, what's your favorite sizes for smartphones and tablets (incl. more functional tablets, such as ipads or android tablets, as well as less functional ones, such as e-readers, if they can be called tablets)? My personal favorite size for a functional tablet is 9.7 (i.e. the size of an ipad), since I think I need more space for more information available for a tablet. I still think that 7 inch is a little too small for all the rich content, but it's okay for an e-reader, such as the kindle fire, which is a little more than an e-reader. In terms of smartphones, the size range that I prefer is from 4-4.3 inch. The Note is probably too big for me.So what's yours?

(pictures from Google)

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UPDATE:

Forgot to mention laptops. My personal favorite size is 13", the size of macbook pro. 11" is too small to see contents comfortably. Words are kind of jammed a bit. 15" or larger is just much less mobile for me. I've seen friends carrying their 15" Macbook Pro, and it looks gigantic. I can probably accept 15" if it can be made ultra thin and light, such as a 15" Macbook air or something.