Leveling from 58-80: Outland and Northrend Recommended leveling paths for level 60-80 players in WoW. Includes best zones in Outland and Northrend, as well as notable quests and rewards. Leveling from 80-90: Cataclysm and Mists of Pandaria Recommended leveling paths for level 80-90 players in WoW. Includes best zones in Cataclysm and Mists of Pandaria, as well as notable quests and rewards. Leveling from 100-110 in Legion How to level quickly in World of Warcraft Legion from 100 to 110. Includes heirlooms, assaults, useful items, and experience boosts. The Big Bag Guide This guide covers bags from drops, quests rewards, vendors, and professions. Additionally it also covers item type specific containers.
Lastly: The zone order I recommend for Horde is Vol’dun- Zuldazar- Nazmir. Vol’dun is definitely the most challenging of the bunch and having the use of your Legion gear and leggos will smooth this zone out. Nazmir is the easiest of the bunch which is nice when things start to get a little grindy past 116. For Alliance, I recommend Drustvar- TS- Stormsong. Same logic as the Horde side, in my opinion Drustvar is the hardest and Stormsong is the easiest for when it gets grindy. I would recommend you waiting to do any of the War Campaign until you are capped because it just takes you out of the way. I also recommend not killing a single rare mob or picking up a single treasure because in my experience it is just not even remotely worth it. The gear scales up on the rare mobs so its smarter to keep them till 120 anyways. After you are done leveling, I do recommend taking the time to do all the quest at the Faction Outpost in your enemy territory. They do provide rep for the Honorbound which helps. Most of them are quite easy. If you do not level in Warmode, you will usually hit 114 from your first zone, 117 from your second, and cap 120 about 2/3 in your final zone.
Heirloom experience should be boosted, now that zones scale. If a zone scales along with me, it shouldn't matter if it gives me 20 levels instead of 10. I'm still enjoying the experience, even as a veteran player. I don't need to see every zone on every character again; that's the point of heirlooms. I can still enjoy the leveling experience, and the scaling, and the full outdoor experience of the zones -- and still get to the end game content I enjoy in a somewhat reasonable time as an employed adult. And the change wouldn't affect new players.
Congratulations on reaching Level 120! There are a myriad of new things to do. The first thing you should do is head to your faction hub ship where you have been doing your mission table quests and footholds to pick up and complete the quests necessary to unlock World Quests. World Quests will provide you an opportunity to grind reputation levels, acquire gear, and gather Azerite. There are tons of new things to do that we will cover in our Level 120 Battle Guide found here: Level 120 Battle Guide