While Season 6 had diamonds in the rough (Not Normal, The Slumber Party, Suction Cup Symphony and more), it also had some really atrocious episodes like Choir Boys, The Splinter, Pet or Pests, and The Clash of Triton. Even though it is my personal least favorite season because of occasional unlikable characters, weak writing, and some gross outs, it still had some quality. Still mediocre, but not very bad.
Season 7 may also have some gems like Enchanted Tiki Dreams, Back to the Past and Squidward in Clarinetland, but it also has really bad episodes like APFG, OCM, Someone's in the Kitchen with Sandy, and Big Sister Sam. Overall, it is a pretty bland season compared to the episodes from past seasons, but it is not horrible.
I'm calling this a stalemate between my 2 least favorite seasons of my favorite show.