All three have very expert areas on the mountain; when it comes to ranking the hardest stuff on each one it really comes down to that season's accumulation. I've done the Big Couloir at Big Sky as well as Corbet's at Jackson - both were incredibly intense though I did them late in the season when they were on the tamer end of their average difficulty. The initial drop-in for Corbet's Couloir can range from 5-10 feet to up to 20 or so depending on snow accumulation, which makes a huge difference to the difficulty of the slope. Likewise with the Big Couloir, it gets way easier towards the end of the season when the rocks bordering the slope are covered over, effectively widening the trail.

I've only skied Whistler/Blackcomb once, and don't remember the names of the harder bits, though the hardest stuff I encountered there was more mainstream than at either BS or JH. They do a lot of heli there though, which i'm sure is incredible. JH has a great sign dedicated to the difficulty you may encounter.

In any case, its very true that the most challenging mid-atlantic slopes don't hold a candle to the expert terrain of many of the mountains out west. It also takes an insufferable douche to expect that they would, and to complain about it.

edit: I've spent a fair amount of time on these mountains, and seen plenty of all of what that sign complains about (I ski raced for a while and was a racing coach for a bit). Frankly, I don't mind most of it - I love that people of all levels are having fun and challenging themselves. My only complaint is when skiers and snowboarders who decide to attempt the blacks do it in a way that is unsafe and ruins the experience for others. Make regular turns so people overtaking you can anticipate what you're doing (S's not Z's, please), and if you're going to zig zag then at least do it off to the side of a trail rather than traversing it each time. And for god's sake, when you decide to stop for a bit, do it where you're visible (not under a roller or jump) so you don't ruin your day along with someone else's.