I have been very disappointed with Mavic wheels over the past 10 years. That being said, the Cosmic Elite is an older design and slightly more aero (should be 30mm deep, not 19mm). The Ksyrium is a newer design and touts being "light", although 1600g does not qualify as a light wheelset in my book.

So, among the three, I highly recommend the Eastons. Everybody I know on that brand is quite happy. However, I still agree with ptle that a quality custom set would cost about the same and meet your desired specs. At your weight, you would be happy with a Kinlin XR-270 rim with 24 spokes up front and 28 in the back. White Industry hubs for high quality or Novatec/Formula to cut costs but still have a decent set of hubs. That would be very sturdy yet reasonably light. Psimet.com is a highly recommended builder with these components.