Alliance.
Horde questing in Vanilla Barrens is absolutely brutal.
But if you can somehow stomach it, or power through it, or ignore it, or by some twist of fate you actually like the aesthetic of the barrens; then Horde picks up a lot in the coolness factor after.
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Horde wasn't the bad guy in vanilla. The factions weren't pidgeonholed into good and evil back then.