Album rankings are revealing, esp in the USA because they don't pay a premium to vote by phone on the show - therefore the winner is not always the most popular person but the one whose fans vote the most times - there is no financial penalty for voting 100 times versus once. But when it comes to laying cash on the line you can see that Chris Daughtry was the most popular from the last season. I suppose it may also be related to what is selected to go on the album.
I also think when you vote on talent shows you are not necessarily voting for who is the best but maybe to give someone the chance to break through that would otherwise never make it - Chris Daughtry would likely be able to get a record contract by walking in to any big producer and doing his stuff, Taylor Hicks would not, so I never supported Chris (I supported Elliot who lacked the looks and style but had a great voice). I think we also vote for the underdogs and oddballs to try to send a message to producers that we don't just want identikit performers all the time.