It was fantastic through Nighthold

ToS is one of the worst raids in WoW period

I cannot disagree more. Emerald Nightmare was genuinely one of the worst raids Blizzard ever made, the Mythic tuning was completely fucked and there was really only 1 good boss and that was Cenarius.

ToS is one of the better raids Blizzard has made, there isn't really a single bad boss in the raid. I think the real problem with ToS is that it was a very difficult raid on average and unlike most past raids, increasing item level made little difference to your ability to kill bosses. Even transmog groups in BFA and SL will skip KJ because if you don't know the knockoff pattern you will insta die in the transition.

And in terms of Legion overall, Return to Kara and the subsequent splitting of it into 2 dungeons was the best dungeon Blizzard ever made. M+ has easily cemented itself as the most popular content ever added to the game post launch, Legendary system really didn't work well until 7.1.5-7.2.5 changes came in.

I think there's very good reason Legion was such a well received expac. It had a shit load of content and that content was done mostly very well.