I think Zoe's unpopularity was much more marked than the general feeling towards Ali- Ali has only been in the dance-off once, people don't seem to hate her. You should have seen some of the threads about Zoe in series three
Zoe basically couldn't do anything right for the public. The judges overmarked her latin, she got one of Bruno's punch-the-air "I don't care that you made a mistake, TEN!" moments, she got a bit of a cold and then claimed she had flu, she constantly talked over Ian... it didn't seem to matter how well she danced, people were not going to vote for her. I don't get that feeling with Ali.
Darren was also more of a surprised to the GBP- he had a journey in attitude as well as in improvement. He looked too tubby to be able to move well, and he turned out to have a good sense of rhythm and performance (/showing off

). He came across as someone who would never take it seriously, but he became really involved in it. He started off "hoping his dance partner wouldn't fall for him", and ended up having a genuine partnership with Lilia. And the two of them never once talked about winning or getting tens.