I think its interesting to define what is meant or perceived by Premium. In sports cars, premium has to do with performance, price and obtainability. Is a McLaren P1 a better car than the Ferrari 488GTB? Or a Porche 918? Hard to tell, honestly, though I think the 918 is the top dog right now, but I digress from my point.
My point is, to me, this category of mid-size "Premium" crossover sport-ute is NOT about performance and capabilities. They are all relatively similar, though some may be slightly more rough road friendly (Discovery Sport) than on-road oriented (BMX X3/4/5). If the description is "premium" then to me it is primarily about the interior environment, and driving pleasure. I thought perhaps I could discern this simply by looking at photos, but you can't.
In my opinion, the BMX X5 interior is simply amazing. You have to sit in it to feel it. It's like the difference between a good pair of Italian made shoes, and maybe a decent store brand, like Clarks. Clarks are great shoes. Quality leather, excellent fit, long lasting. They are the Subaru of this category. But when you try on a hand made pair of Salvatore Ferragamo Italia's, its just a world of difference. They might look similar, but the feel is indescribably different.
Using another analogy, it's like good sporting shotguns. You can tangibly feel the differences between a $5k Beretta verses a $30k Perazzi. Both are excellent, both suitable to the task, both yield similar results, both are similar in appearance, but the Perazzi exquisitely better, with a tangible feel to it that is superior.
Here is a study of interior cabins between the makes discussed. Hard to define what is superior based on the photos alone, but sit in them, and you can tell, without question or hesitation, how they rank in terms of a premium feel.
Land Rover Discovery Sport
Volvo XC90
Mercedes GLK350
Subaru Outback
Lexus NX
BMX X5
Land Rover LR3 (just for comparison purposes - IMHO its the bottom of the list of "premium" interiors)