Personally, I think Sharon's choices are too sentimantal, most of her acts can't stand up to Simon and Louis' acts. Take the blonde girl she looks like Jessica simpson and dresses like sheryl Crow, she has the parsonality of a slice of bread and even the programme editors think so; because we didn't see much of her till she got to the finals.
Then there is the other girl who according to sharon has an image problem except she ups her game during the live show people would be unmoved by her, because she is just there! she is pretty, she can sing but she really hasn't got the X factor.
Tabby is Sharon's most sentimental choice, she is used to rock and roll people like him so she gets him and can handle him, he is better for a different kind of market that isn't as commercial as "X Factor/ Pop Idol", the people who he appeals to are too "cool" to vote.