Tried both in RV-8 and now use only the Mini.
I've tried the iPad mini and found I could NOT see it in the cockpit... ESPECIALLY WITH A PAIR OF SUNGLASSES ON! Not so with a nexus tablet. I can see and use it with my sunglasses. Really just boils down to personal preference. Once you get use to these EFB, you'll never consider paper again!
If your going to go with the mini, I think they are close to releasing a new version. If that is true, I would wait for it.
I'm fixing to buy an ipad. Are there models that should be avoided like the older models, or do they all work fine?