1. Colnago EPS. Lighter stiffer, but same geo as the 40 and 50. Just a perfect blend of things for me.
2. Colnago C40. The best all-day frame ever. Wish I'd never sold mine
3. Principia RS6 Pro. Obviously a bit different to the above. A complete rocket and probably the best alu I've ridden.
4. Casati m:U2. If I still owned it, it would probably feel awful, but at the time it was one of the lightest frames available and it was what I really learned to climb hills on
1. Look 595. I'm glad the ISP craze is over, because that thing would beat you up. Other than that, the main thing in the 595's favour was that it wasn't a 585...
2. Look 585. My first try with Look, after mistakenly forming the impression that Colnago were 'behind the times...'. The 585 wasn't horrible, it was just wooden and uninspiring.
3. Colnago C50. They tried to make a stiffer 40 and instead made a frame that felt heavier. It just seemd a bit charmless and clunky.
I know others will disagree, but that's my experience of training and racing all these frames over a period of about 15 years. That said, if I found a s/h 585 or C50 I'd probably snap it up