When I started I found that Hincapie and Pearl Izumi fit the best for the big and tall rider. I've since lost enough that I can wear some of the slimer cut brands (but even a XXX in some brands are crazy tight on 36 to 38 waist). I would recommend Hincapie if you need a place to start. And buy the best you can afford, better to have one nice bib than several cheap ones - your butt thanks you in advance.