All of the below comments are just an opinion.
I hate to say this but I wouldn't get the Cannondale because it's no longer a brand but just a label put out in the same Chinese factory for Dorel Industries that makes all sorts of low priced bikes like GT, Mongoose, Iron Horse, Roadmaster, and Schwinn just to list the ones I can remember. In addition it's a boring bike because everyone has one. That should raise a ruckus among us.
Trek? Really? Everyone and their brother owns a Trek, yawn, another boring choice but it does have Ultegra, whoopee!
So that leaves the Cervelo and the Krypton in my opinion, note I used the word Opinion twice now. The Cervelo is more of a tri bike which is made more aerodynamic because a tri rider can rarely draft another rider, if you want to do that sort of discipline then get the Cervelo, otherwise get the Krypton because it's more of a conventional design making long rider a tad more comfortable as well. Either of those two bikes won't have the boring no second looks like the Trek and the Cannondale will give you.
However having said that you need to ride both and see which you like the best...fine ride all 4 and see which one you like best but don't blame me if you see people on the side of the street sleeping when you roll by on either the Cannondale or the Trek.