I've owned several rain pants but the best designed I've ever found were Burley rain pants. I found a pair of new old stock a few years ago, but alas, they look like they may only last the end of this season.
The thing about the Burley rain paints is that the zipper is 12" long - AND it's on the back of the leg. There is a velcro strap with reflective stripe on it which holds them very tight at the ankle.
Like I said, I've had several rain pants, but none with this design. I don't much care about breathability because I usually only wear them in the winter anyway. Anybody know of pants designed like the Burley's with a 12" zipper on the rear of the leg and velcro staps?