If you want trail centres then Innerliethen and Dalbeattie are worth visting..Ae is ok….Kirroughtree the least technical, but the bit at the end is excellent.
Pentlands is nice and handy to Edinburgh…plenty of riding to be had, but not that technical and as above can be rather bland. Although I quite like riding there as it's a change from roots, rocks, jumps & drops.
Stirling is pretty bl**dy good…..with loads trails and variety..if you can hook up with a local then I would take up the offer. Only 45 mins away and I would recommend North Third, Dumyat/Uni & Mine Woods…plus Cambusbarron is great.
To be honest if your prepared to travel to the trail centres and drive for 2 hrs I would be looking further North..Fort Bill, Glencoe, Mamores and the Cairngorms…..some amazing natural and man-made riding.