I haven't watched an ounce of X Factor this year, so now after watching a bunch of videos of some of the people you're talking about, I bring to you some objective, untainted views...
Diana is exactly what Simon once said - "the most relavent person on the show". She fits in very well with what's in right now, from the sexy-meets-scabby look to the fashionably out of tune singing. I don't care for her, how young she is, or care about her voice troubles. Back when they did Pop Idol they kicked off that fat f*cker who had the same illness and brought in Darius as a replacement. They daren't have done it to her though, she's too trendy and appealing to the audience. Pretty surprised Naitch likes her so much, in truth.
Eoghan is what just about every talent show has - the young, pretty damn bland, in no way special but loved the by the females type of contestant. Isnt he cute? No, not really, and he's not that good of a singer either. If X Factor wants to produce a lasting star, my initial opinion is that this kid isn't it. He'll follow Ray Quinn right down to...umm...where did he go?
JLS...there's not much to say really. A "boy band"...that's about it.
Ruth was someone originally brought to my attention by DraVen (something about wanting to plug her back passage or something), and I trashed her for being a bit boring and predictable, which I stand by. However, in comparison, vocally and pretty much all around, she was better than the others I've seen.
And in closing, not a single one of them is anywhere CLOSE to Leona Lewis.