Betws has always been pretty rubbish for pubs in my experience. I've usually ended up, like everyone else it seems, in The Stables (next to the big Cotswold's). But that's really not that good a pub.
A little walk out of town along the road towards Capel Curig will bring to the Ty'n y Coed which is much, much, much better.
Last time I stayed there I stayed in a b&b which did fantastic food, and local real ale. The Ty Gwyn Inn on the A5 just as you approach the bridge into town from the east.
The Spar shop in town probably has the best selection of local ales though...