I have both Rapha and Assos bibs, tights and shorts. I used to like Assos better than Rapha, but my newer Assos, with the two sides that aren't stitched, are not as good as my other chamois. Now my "go to" bibs are Rapha (or surprisingly my DHB's from wiggle.com are extremely comfortable-would choose before my Assos).

I think a lot of this is personal preference but my list right now in order of preference would be:

#1) Rapha (last couple lines have been great!)
#2) DHB from Wiggle (surprisingly amazed by their "higher-end" kits--their great prices with high quality put
them very high on the list)
#3) Assos (newer gear is not as good as previous version in my opinion)
#4) Giordana (my first "good" set of bis/shorts/tights, would definitely recommend)
#5) Castelli (be careful what you buy, cheaper stuff is crap, higher lines are very good)
#6) Performance Bike (their "pro" line, I've never tried their very cheap lines)
#7) Pearle Izumi (a lot of variation with their gear, higher-end stuff is very comfortable)

All from personal experience