Castelli Aero Team....All the shorts you'll ever need !!
Never tried Rapha so cant comment, but Assos are not for me, the pad is like a nappy and not worth the money imo!!
Here's a quick comparison from the Rapha and Assos bibs that I currently own:
Rapha Classic Bibs - A more 'relaxed' comfort fit with a good pad. Well made and they look good.
Rapha Pro Team Bibs (latest generation) - Fantastic quality, excellent 'compression' fit but they wont work for a short rider with thick legs. It might sound like a cliche, but these are all-day riding bibs.
Assos F1 Uno - Pretty much the same level as the Rapha Classic but without the looks.
Assos t607 - On a par with the Pro Teams in both fit, pad and ride-ability. The addition of a roubaix type lining makes them ideal for UK weather. I also like the 'stealth black' look.
Of the four the Pro Team bibs are my faves but the t607 is a very close second. Worth every penny IMO.
I love my Assos F1 Uno's to bits , but the Lycra has gone see through at the back , got loads of life still in the pad and the rest of the shorts , just seems the rear is wearing thinner.