I saw a few guildies in chat asking if there’s a way to tell which quests are story quests. I had the same question and found an addon that helps me a lot. It’s called BtwQuests. It’s the solution that I saw offered the most in the forum threads that I researched on the issue.
It has its own window that shows quest chains in a flowchart format. It adds an icon to chains that are required for the zone storyline achievements.