I test drove both. Loved the MDX. Hated the Lexus. Like a big, clunky truck. And the trunk opens sideways. Which is awful.

Get the Toyota Sequoia. Bigger than either, and you won't be telling the whole world (or at least the part of it that knows cars) that you got taken to the cleaners because you bought a re-badged Honda or Toyota. Because that's what an Acura or Lexus is