Season 4- The worst season in it's 10 year run. Lana and Witches with the whole tattoo arc ruined it
Season 5- What season 4? By the second/third episode almost all of last seasons troubles are forgotten. It was a recurring thing in Smallville.
Season 6- I just remember Zod/Lex VS Clark
Season 7- Bizarro and the Veritas arc that went around in circles.
Season 8- No Lex. The introduction of Tess.