A:
I am 6', weigh 200 lbs, have a 43" chest, and a 38" waist. I have tried on both the XL/XXL and the M/L, and for me the M/L was a much better fit. I could have worn the larger size, but the smaller size was better regardless of whether I was wearing a cold weather jacket or a simply a jersey. I am one of those people who sometimes wear L and sometimes wear XL. This vest is nicely adjustable to accommodate extra bulk clothing if necessary.