At the moment, Sam is massively overrated, more so than any of the other contestants at any stage during the competition. I think it's only been in the past 4 shows, however. Since Week 4, I think the show has been ever so slightly engineered to give Sam the limelight and ensure her eventual victory. The engineering is working and becoming more blatant as the weeks go by. I'm actually pleased the favouritism is so obvious--it generates a teeny weeny bit more support for the other contestants.
Rachel and Jessie have been, in my opinion, both overrated AND underrated by the panel and ALW at various points in the competition.
Rachel's been excellent in the past couple of shows, yet criticised; and she's clearly the best actress, which is barely ever mentioned. In her "blip" week (For Once In My Life IMO) she was praised. Rachel's my favourite and has been from the start, but I did feel at that point that she wasn't being given constructive criticism but made to think she could do no wrong which definitely wasn't in her favour. Since the sing-off, she has improved dramatically, showing that she can cope with adversity and pressure admirably. In my opinion, that is, but I'm a bit biased. Hope you don't mind!
Jessie's a bad actress, again never mentioned, but I like to give credit where credit's due and the judges no longer point out that she sings beautifully and strongly and has fewer tuning issues than the others. I think her weaker points are covered over and excused by the judges, which differentiates her from Sam as her weaknesses are praised as major strengths! Quite bizarre.
Jodie, I think, has had the fairest run, and I've tended to agree with the judges' opinions--with the exception of the disastrous comment this weekend (but let's not get into that). She's still in the competition not because of any engineering or manufacturing by the production team, but on talent and the support she has won, and my hat goes off her for that.
Essentially, I think Jodie and Rachel are in the final four on their own merits; Sam and Jessie have had some help along the way, and Sam significantly more than Jessie.
Gosh that was a long post! Sorry everyone!