I'm 6'1" (185cm), 182lbs. with 26" (66cm) thighs, 15" arms and I wear 33W pants (actual waist meas. = 35"). I'm large for a cyclist and have been using the Castelli Ergo Tre bibs. The Kiss 3 pad is ok but only for shorter rides - 20 miles or less. It leaves me sore though and prevents me from riding on consecutive days. Lighter/smaller cyclists though seem to really like the Kiss 3 pad. The bike seat also makes a difference.
I recently received the Castelli Endurance Bib. I ordered an XL in black and it fits me perfectly. They have a visually simple design and the fit feels a bit odd compared to the contours of the Ergo Tre. The only standout graphic is the logo. The lettering on the leg hems is attractive and the leg grippers are a wide band of vertical rubber stripes that do a great job without pulling hair. The overall subdued look of this bib actually looks great when paired with any top. The garment quality / craftsmanship is excellent.
Now for the really important part: BUY THIS BIB! The Progetto X2 chamois (pad) is incredible. On my first ride I instantly knew - despite my firm seat - that I could go 50 or more miles pain free...and I can ride consecutive days. I now have several rides with this and I haven't gone back to my Ergo Tre bib. This chamois is used in Castelli's most expensive bibs. At this price they should've sold out already!