JPW is #1 on that list by far. Steel chin or foolish pride, either way, he was getting back up time and time again.
Freddie was tough as well, but had a lot more ... mass... providing some added protection
Coker, hurts, and gmac are next in order. But, their OL play comparatively to most of JPWs years isn't apples to apples.
Brodie is up there IMO, dude took some beatings too. And Freddie had the advantage of not being able to feel much of anything most of the time due to his off the field activities...