Wow, this is a huge question especially trying to wrack my brain for the memories of each season. I actually did not watch season 1 and only caught the tail end of Season 2 but here are some thoughts of each season for me.
Season 2 - I only saw performances of Ruben Studdard, Clay Aiken and one song by Kimberley Locke. The minute I heard Clay sing I was hooked. I caught his performance of "Unchained Melody" originally by The Righteous Brothers and loved it. Ruben was just okay for me although I did buy two of his cds eventually. I have bought everything by Clay and feel this guy can sing anything. I have the first cd by Kimberley but only like a few of the songs although I do think she can sing.
Season 3 - My favorites of this season were Diana DeGarmo, La Toya London, George Huff. These are the ones who made the top 10. I also liked a guy named Matt Rodgers who made the top 12 (he was eliminated in the 12th position). I never cared for Fantasia except for one song which was "Summertime". I do not care for someone who screams their lyrics. I have bought the cds of George Huff and Diana DeGarmo.
Season 4 - I actually liked most of the top 10 in this season but Bo Bice, Anthony Federov, Nadia Turner, Jessica Sierra and Anwar Robinson were the standouts for me. Carrie Underwood was a good singer but she mostly sang country-like hits which did not thrill me however I loved how she sang "Alone" by Heart. Constantine Maroulis was okay but his standout performance for me was "Bohemian Rhapsody" originally by Queen. At times I liked Scott Savol's performances. Vonzell Solomon could sing but was just okay for me. I would have loved to see more of what Nikko Smith could have done but he was eliminated early however on the tour which I saw he was fantastic.
Season 5 - I was fascinated with Taylor immediately and eagerly looked forward to his performances each week. He is my top favorite idol of all time as you many have guessed. My other favorites of the top 10 were Ace Young, Elliott Yamin and at times I liked performances by Bucky Covington, Chris Daughtry and Paris Bennett. Mandisa was great however did not always choose songs that were good for her. My top favorite performance
of hers was during 50's week with Barry Manilow. Speaking of mentors, they had several on this season that were interesting and did well by the contestants but Barry Manilow and Rod Stewart were my top favorites.
Season 6 - My top favorites of this season were Melinda Doolittle and Lakisha Jones. I really liked every performance that both of these girls did.
Blake Lewis was interesting on a couple of his performances. My favorite performances by him were "Time of The Season", "You Give Love A Bad Name" and the song he did by the group 911 (sorry I can not recall the name of the song). Phil Stacey gave 3 performances I really liked but his choice of song on others was not so good however I did buy his cd and like it. Chris Sligh left too soon in my opinion. I loved his voice and liked all of his performances. The only performances by Jordin Sparks that stood out for me was "Livin On A Prayer" and "I, Who Have Nothing".
Season 7 - My top favorites from the top 24 were Asia'H Epperson and David Hernandez. Sadly these two did not go further. From the top 10 my favorites were David Cook and David Archuleta. However I did like some of the performances by Carly Smithson and Michael Johns. I intend to get their music regardless. None of the other contestants of this season really interested me that much although I did like a performance here and there from the remaining group. Amanda Overmeyer interested me alot but she also was eliminated too soon.
Coming in January 2009 is Season 8 and hopefully they will have some good contestants who will peak my interests.