Test ride them and see which one feels best. I just bought a Felt Z85 and love it.. the anodized aluminum, attention to detail, 105 components, upright posture, ride feel. It felt just like the synapse for quite a bit less money to me which is why I went for it over the synapse. It has carbon fiber forks and seat post as well. I didn't like the ride of the CAAD10 by comparison and the trek 2.1 was fine, nothing special though and more expensive for nearly the same components. I still need to take a high res picture the bike yet.. maybe Friday.

I personally think it is great looking too and it's not really common around here in my particular town so it gets a few looks. Looks more expensive then it is. It comes with 700x25 wheels which is my preferred wheel for handling bumpy roads a bit better. And up here, with temps that get below -20 in the winter numerous times, the frost heave definitely takes it's toll on roads.