Game of Thrones in the early seasons had interesting intrigues and there were a lot of options for who could be the next king or queen. Plus it had a way of making you care about a character before they were killed off. Yes I'm still salty about Oberyn Martell.

Then the politics and intrigue became increasingly less important as it became Dany + allies vs Cersei + allies. Yes there were a lot of other issues in the later seasons such as the whole fast travel issue, but that was just the tip of the iceberg.