Swinley 🙂
There's bits I like about the North, the M1 and the M6 southbound I think are my favourite trails :p
In all seriousnes, there are some good trails in the North, Warncliffe, Blacka Moor, bits of Grizedale, the switchbacks coming down of cut Gate, etc but we're talking isolated bits of trail that sometimes take a 2 hour ride to get to the top of.
Swinley or the Surrey Hills has more quality singletrack each than the North of Englnd had in total. And you can do a 20mile ride entirely on the kind of trails you'd slog for 2 hours to get to up north just to ride the kilometer of singletrack at the end!