Parkin Clough looks crazy. I'm going to have to ride that soon.
Thing is with these descents, and why the Peaks is so good for biking, is that they're all a bit different. Rode Cavedale on Saturday for only the second time and it's a great descent right from the open grassy section at the top. The rocky sections are fun but only half of the story; the place is like a natural freeride park with loads of hips, bombholes and drops up the valley sides. I was even eyeing up, somewhat over-enthusiastically, some big drops off the cliffs when it opens up underneath the castle.
The beast is fun because it's so fast. Once you have done it a few times there's plenty of options to take more challenging lines, hit the drops etc. And there's a couple of good corners to rally it around. Just have to watch out for the showstoppers!
Chapelgate is probably the hardest out of these three IMO. A couple of sections where there's only really 1 line and if you're not on it you better hope you've brought your magic tyres or you're done for.
What about the PBW along Roych Clough? There's some pretty tough lines along there if you hit all of the drop offs.