Objectively speaking I think it all depends on what you are looking for, I like Cwn Carn, and Afan, however they are both close to me (Afan 15/20 mins, Cwm Carn 30/40 mins) so easily doable if I only have limited time, that said j do like Afan as I can spend a fair few hours and do a couple of different trails. North Wales wise, Betys Coed is good for the Marin, get there first thing, do that and then Llandegla on the way back, as in my humble opinion the cafe at Llandegla is superb, but then the best Welsh trail centre cafe to me was the original one at Coed y Brenin, before they moved across the road to the new centre. Saying that though, I do also enjoy a post ride pint of Reverand James at Afan Lodge.