That is all up to you my friend, and what you need. You didn't specify the other years of the other cars, and what other brands you're open to.
Here's my breakdown:
The Escalade is the biggest one out of the bunch, and unless you're carrying a boatload of people, or cargo every day, this ISNT the choice for you. The others are sportier, and handle way better. NExT.
The BMW X5 doesn't have the best reputation for reliability, nor does it have low maintenance/repair costs, which is going to burn holes in your pocket, along with the gas bill. NEXT.
This leaves the RX, the Audi and the MDX.
The Audi is german engeneered, and is my personal favorite. It drives like a dream (it's actually based off of the VW Toureg and the Porche Cayenne). It's fast, stylish, and sporty, and you don't see as many of them around as you do the others.
the Lexus is luxurious, but overrated. Everyone and their mother (literally) has one, but they are wonderfully designed, and pretty reliable. If you're fine with a plain jane ride, this is a really good option for you.
The Acura lays inbetween the Audi and the Lexus. The ride is sportier than the Lexus, but it's also not as smooth. The design is really edgy and sporty, it's a hate it or love it design. The interior is pretty modern, and this is a great choice if you like the styling.
I would personally go with the Audi myself, because i LOVE german engineered cars, but all are great options- test drive them yourself, and see how you feel in them before you give a final verdict.
