New Road bike – recommendation

Looks like they are all aero
Looks like they are all aero bikes of a relatively similar weight level, with similar level hi-end wheelsets and you are fully set on Ultegra Di2, so if you really can’t try any of them out, maybe you should just go with the one that is the best price..unless you want to stretch to one of the others cause you strongly prefer it’s looks.
For me also the Giant and the Bianchi have the nicest looking geometries, but it’s just personal taste.
Maybe somebody else with experience (these are all very mainstream/popular aero bikes) will chime in with a stronger opinion about which one you should choose.
I noticed that the Pinarello says the frame is T700 carbon and I thought that was now an older Carbon grade usually only used on entry level standard carbon road bikes, but I’m probably wholly uninformed. Besides, the others don’t even mention anything much about the carbon they use

Of your list I’d run with the

Of your list I’d run with the Bianchi, because of its looks.  The Venge however has been ridden to more TdF stage wins.

Also consider a Cannondale System Six and Trek Madone.

Personally I would build a bike based on my favourite frame, wheels, and Sram eTap which to me makes the other electric systems look a bit ‘last season’.  There are some good deals on the 11speed now that the new group has come out.

The Giant, but get that front

The Giant, but get that front wheel the same depth as the rear.  looks really tiny, spoils the look