It depends if you mean just dance ability or appeal to voters as well. I think:
Contenders, i.e. will score highly with the judges and whose popularity will be untested for weeks:
Peter
Jamelia
Helen
Georgia
Kellie
(Kirstie could be a judges' pet or a dark horse I'm not sure)
I think if one of those turns out to also have big public appeal they will walk it - but they are all capable of coming across rude/fake/manic/cold if they're not careful. I'd put Peter first as he can dance and he's the most experienced at reality TV and knows the traps.)
Learners:
Jay - if he's as stiff as he looked when I could see him in the group dance, forget it. But if that was misleading or nerves and he can improve, I can see him having quite tough judges' comments and scores but that sometimes increases people's vote from the public. Masses depends on if he and Aliona get on. He seems such a sweetheart but he could be Thom levels of disappointment if he turns out not to be able to dance - and Thom got better but he couldn't get over that initial disappointment of his first dance in people's minds. I hope he's going to surprise us.
Anthony - same again, could be stiff and awkward but if he can dance or can learn he'll be liked for it. His injury makes it tough for him though. Oti is an unknown quantity, but I think they look a good team.
Katie - I think there is a big part of the voters that would like to see Anton do well, and that and her ability could take them far. Or Anton won't be able to stop clowning and they won't click as a partnership, not sure yet.
Anita - I really like her, but it depends on if they can work as a partnership. Gleb was a bit underwhelming to me on the launch show.
Ainsley - I think he can dance, he certainly seems musical and Natalie's a fantastic teacher. But he's likely to get stuck with a lot of the stupid props and stunts, and he might be annoying.
Iwan - he's determined and a sports man and I don't think anyone understand what gets votes better than Ola. However, he needs to calm down a bit - I really like him and even I was thinking 'OK OK enough with the stuff about taking your shirt off now...'
Duffers
Daniel, Carol and Jeremy - but I think they are all likeable, popular and charming, so if their pros can get a nice ballroom out of them, they might not be first gone. Jeremy looks the most likely to go first for me but I hope not. I'm assuming it's going to be two dances before the vote this time, so they each need the ballroom on the week people vote, not the Latin.