Jade fans have every right to want her to win because they think she's the nicest. Just like Tahan fans want Tahan to win because they think she's been the most honest, or Tim fans want Tim to win because they think Tim is the funniest etc. Its all a matter of opinion.
IMO Jade is definitely the nicest. Watch some of Tim, drew and Tahans rants about people in the diary room. Do you honestly think Jades bitchiness is at the same level as those three? I mean can you imagine Jade mocking someones eating habits, saying she has a better personality than everyone else, call people boring, annoying, saying their stories are boring, mocking people etc. Jades bitching almost never goes beyond her just venting about things they've actually done. She doesn't belittle them too much. She just says what she doesn't like about their behaviour and that's it. Other than the "die in a hole" comment( which she took back the moment she said it and then apologized to Tahan for), I can't think of anything she's said that's been too nasty. That's not to say the others aren't nice though. I just think Jade is the most consistent at it.