I have no use for car seats but think there are multiple points to attach. I did however look at the MDX and the Volvo XC90 before getting my X5 4.8.

I found the MDX lacking in power but if you are looking at the X5 3.0 that is not the case. There is a differecne in materials used and for myself I did not like the visability out of the rear. There seems to be a much larger blind spot in the rear quarter.

It depends what you want or do not care about.