Allison never really connected with the fans, which is why she ended up in the bottom three a few times despite being awesome week in and week out. If the judges had given her 5% of the push they gave to Megan during the few weeks that she stunk up the show, then maybe she'd be in the top three right now and be considered a favourite. Nobody ever called Allison "different" or "current" or "commercial", or even "beautiful" (not even Paula) -- all of these praises were heaped on Megan, undeservedly, because she was a talentless flake who was exposed as lazy and arrogant and shown the door by the fans when these "qualities" became impossible to ignore. On the other hand, Simon was right in criticizing her personality and the way she came across on camera. It wasn't right for him to remind her of this on a weekly basis while downplaying all of her strengths, but he was right on concept. Like Jason Castro last year, you can only go so far as a bored stoner on "American Idol" because people don't want to vote for someone who appears unmotivated and doesn't care too much about winning or losing.
So it's going to be Adam vs Danny in the final, which is exactly what the show's producers and the four judges have been pimping since Hollywood week. Adam can be great when he doesn't go AYYEYAEYEYAEYOAEYEY without warning in the middle of random verses, and Danny shows flashes of very good-ness when he doesn't sing in his lower register and reigns in his Hicks-ian tendencies (most annoying: the dancing). He's also burned up some of the dead wife-related goodwill that the producers so nicely
I think nothing can stop Adam from steamrolling his way to the title, but Allison and Kris's albums will easily outsell anything Danny or Adam put out (unless Danny goes the Xtian rock route).