Out of the frying pan Bob.The traffic around Llantrisant/Talbot Green/ Pontyclun is horrendous during rush hour and you can catch queues at other times of the day too.There are proposals for a great deal more housing in the area which are being vehemently fought because of the lack of infrastructure to cope.
The Creigau route to Cardiff will probably be your best bet although some of that is one track.If you go west you will run into traffic at most times of the day in the aforementioned 'villages' which can all be bottlenecks.
A few years down the line I have no doubt this area will be part of the western suburbs of Cardiff.