Duffy is another favorite of mine. Although, I do not think she has either the range or quite the power in her voice that Adele enjoys. Her song writing is also somewhat second-rate to Adele's, IMO. Nonetheless, it is a shame that she seems to enjoy a lot less popularity than Adele....or for that matter Taylor Swift! ( don't get me wrong, Taylor Swift is ok...but IMHO not in anyway as great as the public seems to perceive her, and certainly not more talented ( if as much) as for instance,Duffy).
Duffy is a very genuine artist, very humble. I agree she does not have the power of Adele, but to me she is more understated by design like Dusty Springfield.