A lot of people say that it doesn’t matter, but in my opinion picking the right zone for the right character matters quite a bit. It will definitely decrease your leveling time.
So how should we pick the zone?
Actually it’s very simple. All that matters is the item level of the character.
If I character is item level 700 and higher I would suggest that you start with Stormheim then Highmountain then go to Val’sharah and finally end with Azsuna
If your character is lower than 700 item level start with Val’sharah then go to Azsuna then Highmountains and finish with Stormheim.
If you are wondering why I’m puting the zones in this order it’s actually fairly simple.
Stormheim is definitely the hardest. Generally most of the zone is fairly easy to do, but there are few quests/objectives where the mobs tend to die a lot slower and if you have a character with high item level it’s best to take advantage of the fact that your character is still really strong at level 100-101-102 due to the high item level and finish that zone. Same logic applies why it’s listed last for low item level characters. Basically, so that they can get high enough item level not to have any issues.
Same for Highmountas. Although to be honest there aren’t any hard zones in Highmounts some of the quests will be a lot easier to do if your character kills the mobs faster, that’s all.
Val’sharah – It’s actually a REALLY, REALLY easy zone. The reason I suggest it as a third leveling zone if you have high item level is because once you are done with the zone you will get a item level 800 chest.
Finally Azsuna – It’s again a really easy zone to do. Azsuna and Val’sharah are basically the same level of “hardness”, however since it doesn’t have any worthwhile reward like Val’sharah(800 ilvl chest) that’s why I’m suggesting it as last for high item level characters and second for low item level characters.