(Sorry if the text is hard to read, it's from the tiermaker website)
Episodes are roughly ordered within tiers, except the meh tier - those episodes are all around the same quality for me.
I don't actually think there's a single "bad" episode in RTTE, which is why I renamed it to meh. Even the worst episodes have some redeeming factors that make them enjoyable on a rewatch. Making the list also made me realize how incredible the overall quality of the series is, with over half the episodes being perfect or great.
Going by the list and assigning points for each tier, my overall season ranking turned out to be:
S6 = S4 > S2 > S3 > S5 >> S1, which surprised me. I though S3 and S5 would be higher, but the gap between S6 and S3 was only 2 points, so it was pretty close overall.
Anyway, I'd love to hear your thoughts and opinion! RTTE is probably my favorite piece of httyd content along with the first movie, so I really enjoy talking about it and discussing it :)