Due to the coronavirus, Blizzard has enable a buff, Winds of Wisdom, which increases XP by 100%. Naturally, this is encouraging people to level alts.
I have been leveling a Void Elf Warlock. I'm up to 112 and into Battle for Azeroth. The Legion Warlock campaign was really good. I haven't finished it, as the next part requires dungeons, so I'll go back and finish it at 120.
I'm kind of regretting not leveling one of each class during Legion. The class campaigns are really enjoyable.
In any case, one of the interesting things about Winds of Wisdom is that it stacks with heirlooms. So you can zoom through levels. Or alternatively, you can stop using heirlooms and still level at quite a rapid pace.
I've realized that I really enjoy upgrading gear when leveling. You get a new piece of gear, you equip it, and your character's look slowly changes. Without the gear treadmill, you're just filling in a bar and your level increases every so often. Nothing really changes, especially since Blizzard front-loads most of your rotation.
I wish the XP gain on heirlooms wasn't tied to the piece of gear. Maybe it should be always active once unlocked.
In any case, the Winds of Wisdom buff offers a good opportunity to combine fast leveling with upgrading gear.