It's hard to give advice on this, both because they are all good, and because we don't know what you like or need in your collection.
What Cathe DVD's do you already have and like? What kind of workouts do you like?
It would be hard for me to choose just one of the four, but B&G and LIC are probably my favorites for now (but the other two are so close behind it's still a close call).
If you want a really glute-burning lower body workout, go for B&G. If you want lower-impact, but intense, then go with LIC. If you want something that seems rather fresh and new, and athletic, then DM is what I'd suggest. And a workout that offers options for step, lower body circuit and upper body, then BMax2 is for you.