Seasons 1 & 4, the winner was the obvious standout and never made it to the bottom. Throughout Season 1, the judges seemed to favor Tamyra. She was the early favorite to win and everyone was shocked when she was voted off "early." Once she was gone, Kelly was head and shoulders above the remaining contestants, and received tremendous praise from the judges. In Season 2, pretty much everyone expected Carrie to win. The judges favored her throughout.
Season 2 there were three obvious standouts, Clay, Ruben and Kim Locke. The judges favored Ruben.
Season 3, the three black divas kept splitting their vote until only Fantasia was left, then she sailed to the win with the judges praising her to the hilt the whole way. Simon especially never liked Diana, and kept ripping her because she was too young.
This year is unique in that there is no standout and, other than Kellie Pickler, the judges don't seem to have a strong favorite.
I think they realized that Reuben wasn't going to be the AI they had hoped for and so they pushed for Fantasia. If only they had pushed for Latoya or Jennifer. I liked both of them. Still don't know why they picked the screaming mimi over Latoya, who is pretty and talented. Neither of which can be said for Fantasia.