What is the best ipad mini retina case you know of?

Best depends on how you'll use it. Do you want one with a keyboard? Or a portfolio case? Or a sturdy impact resistant one?

There is no singular best. But there are individual 'betters' as it pertains to your need.

If a keyboard case I'd recommend a Zagg one. I've used one on my 2 for a couple of years and love it. I'd also recommend Targus cases.

Beyond that, knowing what kind you want would be helpful for any specific recommendations.

There are lots of portfolio cases out there that have a cover that turns into a prop. 'Great protection' may or may not happen. Generally protection = bulk.

Amazon is a great place to shop. Even if you don't buy there, you can see what's out there, read reviews and get some brand names to look for.

I've become a big fan of the Khomo Smart Case. Very similar to the Apple case but a fraction of the cost. Works very well.