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I have both a Mini and a 4. I use the 4 around the house and the Mini goes out with me. It's a cellular one and my 4 is WiFi only.

While the screen on the 4 is better, the Mini I find much more usable in terms of size and weight when I'm out and about. So I'd say if you want portability go for the Mini. If that's not an issue go for the 4.
 
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