Trail centre – from my relatively limited experience (never biked in Scotland, though that will be rectified by a road trip in the Autumn) I would say CyB, though I also enjoy the short loop of Penmachno.
Trail – Without a doubt the loop from Edale taking in Royche Clough and Jacob’s. Though I’m doing Cutgate in a couple of weeks *prays for dry weather* so that may change..
UK trail centre, Hebden Bridge
And a big +1 for that. More crazy, rocky, jumpy, narrow, slippery trails than you could shake a stick at, all connected by a well laid out network of trails and roads and with a plethora of good caffs, pubs and chippies at the trail centre in the valley 😉