I agree with that order.

It kind of helped that by the time Oliver Grainger took the role, D.W. was much less annoying as a character than in the first seasons, where she would cry, scream, or whine in many more episodes than she does in later seasons.

Robert Naylor sounded terrible in early Season 11. In "Swept Away" especially, D.W. sounds way too high-pitched and scratchy. He got better by Season 12, though he still sounded higher than all the other actors.

Michael Caloz is my favorite too, probably because he was the first. 

Oliver Grainger is passable, though at times, especially whenever D.W. would hit emphasis, he sounded like he was losing his voice.

Jason Szwimmer, likewise, did a passable job with D.W., a little better than Oliver, but still not up to Michael's level. I will say that at times, Jason's D.W. could sound a little nasally, almost as if she had a cold, but then again, that worked well whenever D.W. would start whining about something.

Can't really give much of an opinion on the others since I haven't watched a whole lot of Seasons 9-15, though I will say that during that time, D.W. pretty suffered the same problem that Arthur did, in that her voice was far too high for her character.