I have a good idea how I'd rank the first four seasons but the last four are a bit of a blur so it's more of a hunch. I do recall feeling less and less interested season 5 onwards though.

S2
S1
S3
S4
S5
S6
S7
S8

Season 2 takes top spot for me because it's the season that persuaded me to get the books. It was Tyrion's best season, and the battle of the blackwater was the best battle sequence the show ever did, imo.