I decided to level my nightborne hunter for fun. He is about to reach level 60 which opens many different paths. On my main I spent most of the time in Outland which I enjoyed. One or two in Pandaria and Northrend, maybe one in Draenor. Any suggestions about what I missed before and should do now? I am mostly considering splitting time between Northrend and Pandaria, maybe a little Zangarmarsh cause I loved it. I enjoy the settings and music when I’m playing. Second would be plot.
Without knowing which specific zones you played through in Outland, the one or two in Pandaria and Northrend, and the maybe one in Draenor, (besides Zangarmarsh which you did mention, and the starting zone areas of each of the continents… except Northrend which has an option of 2) it’s pretty hard to make any recommendations. 
While the Darkmoon Faire is up, buy some Inky Black potions. Zangarmarsh is one of my favorite zones to use it because of all of the glow effects on the mushrooms.
For Northrend zones, I think Storm Peaks is my favorite. I like the story and I really enjoy the music. (Although it is a bit annoying if you don’t have the 280% flying due to all of the back in forth to Thorim’s super high tower.)
In Pandaria, I always enjoy Kun-Lai Summit. I’d recommend doing it from a ground mount. I find it’s one of those zones where not just flying to objectives really helps with the immersion. I also enjoy the Valley of the Four Winds/Krasarang Wilds story. (I love the ending because I’m a big sucker for “Cavalry” moments.)
That is helpful thank you