I’ve ridden the Mynd once. i get the impression it’s one of those places you need to know where to go. I seemed to spend a lot of time on road and tracks and not much on proper off road trails. The off road trails were great but over in a flash and before you know it you’re back on a track or road. I’m sure if you were guided by someone in the know there would be loads of stuff you just wouldn’t find if you’re just meandering around on your own. Maybe you could pop into the bike shop in Church Stretton, Plush Hill Cycles, and get some advice on local routes. I bought my bike from those guys and they are really friendly.
Cannock is a trail centre, and I prefer natural riding, but also enjoy trail centres. There are some pebbles but that adds to the challenge and depending upon how much of it is currently closed (and some sections are currently closed) they’ve done a reasonable job of keeping you off fire roads.
For your situation then Cannock would be nice and easy to ride on your own, it’s easy to split it up into sections and repeat certain sections that you might enjoy, and if you fancy it you can always take a look at Stile Cop for some jumpy stuff.
I’d choose Cannock over the route around the Mynd route that I did, but if you have some insider knowledge on the Mynd then that probably has the greater potential.
There is some other riding nearby the Mynd though, a good number of woods and other areas. They might be worth a look too.