Supernatural. Imo season 5 was a great ending and a nice bittersweet way to end the series, instead they just kept going and the plot got too convoluted and I stopped caring. Might rewatch at some point, but idk if I'll watch past season 5
Honestly, it's worth skipping season 7 if you do make it that far. The leviathan are one of the worst television plots in history imo. That said it gets pretty decent again for a few seasons.