I can recommend the Western approach, following more or less , but not slavishly, the path as shown on the OS map( 200 , 1/25,000 ) A bit sqidgey in places, but nothing to worry about. No man swallowing bogs here. You will need a car to get to the start, at a ford over the river at 835/566 approx.
A trip around Lyn Brianne reservoir is worth the effort too.