I am also (but not too seriously) looking at 3 of the bikes listed in this thread (mainly to get disc brakes) on about half of the OP's budget, i.e., $5,000, and so am aiming for a mechanical Ultegra build. I can afford but do not want to spend more because I am under no delusion that I will become any faster. My uninformed opinion:
1. Bianchi Infinito CV: Italian premium (yes I know the frame is made in Taiwan), renowned celeste color, weird (more fragile?) seat post. Geometry closest to my current road bike.
2. Argon 18 Krypton GF (not Pro): Intrigued by review on Gran Fondo magazine, but have not found a dealer to try it. Must get it built to get Shimano Ultegra components, but then at least I can get a short cage rear derailleur.
3, Canyon Endurace: Least expensive, but only comes in black. My leg muscles are not strong enough for 52/36, so requires swap to 50/34 on day 1. Waiting for Canyon showroom in Carlsbad to reopen in mid-June to take a look and ask if that is possible.