Well, Im super uber biased, and love the Madone. I'm not very educated in the others. But what I do know, is that the availability of the 5.1 is terrible right now. It's being replaced with the 4.7. Same components, but TCT carbon, rather than OCLV. So... unless your LBS has a nice stock of the 5.1 in your size, ask them what they've got and how long it's going to be around. Good luck choosing what you want!