As far as the sequels:
DA II received a lot of flak, but ignore this and try it. I actually liked it better than the original. It was flawed, sure--I won't deny all the reused assets or a few places that seem rushed--but they tried to break the standard BioWare formula with the story. Also, Varric is awesome. The first one is good, but slightly too long (confession: have never actually fully completed a playthrough yet without getting distracted by other games) and mostly just tells a traditional fantasy well.
Haven't played Inquisition, can't comment.
My real favorite BioWare franchise is Mass Effect, which you should also check out.