I don't think any of the judges are perfect, and they all get it wrong in how they put comments across sometimes.
Craig's comments are closest to his marks so in that respect he is probably the most consistent, but the tight time constraints means he often comes out with a shopping list of faults, some of which don't always mean much to the public or, I'm guessing, the celeb (e.g. "crumbly transitions"). It doesn't help that he often gets shouted down by Len or booed by the audience before he can get out his one small positive comment at the end.
I've never joined in the general hatred for Alesha-as-judge and I do quite like her in the role especially as she has grown in confidence. She does overmark but given that she, more than any of them, judges on performance rather than technicality that can be forgiven in her more readily than it can in, say, self-proclaimed "ballroom expert" Len. When she does have something more technical to point out, she tends to identify one area for improvement which gives the celeb a single point of focus.
Bruno can talk quite a lot of sense (in terms of critique) but it so often gets lost in his swirly arms and general bonkersness that you remember the daftness and forget the sense. He can also be quite cruel and cutting, much more so than Craig on occasion but he's more likely to get away with it because he does it with a maniacal laugh and an overblown impersonation of whatever just went wrong in the dance.
Len. Where do I start with Len? Inconsistent, grouchy, nasty, holds a grudge, wants to be seen by the public as the avuncular uncle and by the other judges & pros as the respected headmaster who should not be talked back to, is as likely to mark a dance in response to Craig's comments rather than his own opinion, impatient, intolerant, sexist....I could go on, but the steam coming out of my keyboard is making it hard to see the screen...