Smooth flowing road riding SE Wales

I’m a bit fed up of shitty roads and silly steep climbs. There are a few nice open relatively well surfaced  roads like the big Valleys climbs,  the mountain road from Markham to Tredegar, or the one from Chepstow to Usk, but I’m interested to see what I’ve missed.

What are your fave roads to ride on down here? I start from Cardiff. Even the good roads involve some crappy riding to get to. I do the Bwlch from here via Maesteg and whilst the climb is glorious the rest is meh.

Should head up to the Sennybridge firing ranges, tarmac on those is good, most of Powys seems to be getting top dressing at the moment otherwise.

Edit to add that I don’t road ride, those are just the smooth bits I drive whilst covering Mid, South and West Wales for work.