Currently I have ten Colnagos, and while my Masters (Olympic and Piu) sure have great paint jobs they're not my "best riding" bikes by far.

My preference would be my C40, closely followed by my Superissimo and both my Nuovo Mexicos (Zoetemelk liveried Nuovo Mexcio is the prettiest bike ever), my 1999 Tecnos, my Crystal and only then the Olympic and Piu. Funnily enough my other two Tecnos are my least favorite for whatever reason.

Personally I just find my Masters not as lively compared to the much "lighter" feel of the Mexicos and the Superissimo. I just always associate my Masters with the hard slogs through nasty winter and spring weather that I use them for
The C40 is just all about day long comfort to me. I rode that bike home when I bought it, 105 miles in jeans on a saddle I didn't even like, and it was just a joy from start to finish.
(anyone need a Selle Italia Max Flite Gel Flow Team Edition in white but with a slight blue hue ?)