I level a lot of alts, and I know a lot of people do too, but frankly I almost always take the same route, which is:
Elwynn - Westfall - Redridge - Duskwood - STV both sides complete (love it) - Western. Plague - filler zone until 58 - Outland until 70 - Northrend until 80 - Pandaria (never cata) - WoD (shadowmoon then treasures - Legion ( Highmountain and stormheim) - BFA, which I start in Drustvar.
You can see I have more of a ‘classic’ route, maybe because I started out way back in TBC.
While leveling I do about half of the dungeons once, for the quests. No pvp.
So I’d like to know your ‘route’. What zones are an absolute must for you, the zone you look forward to each time you level an alt (for me it’s STV, whole outland, Howling Fjord and Jade Forest).