Quantity? Profit margin? Speed at which inventories are depleted?
Best is subjective, but simply based on longevity, the Peavey Bandit has earned a place in the pantheon of guitar amp history.
Ok, quantity.Best-hyphen-selling, means "the one that has sold the most units". Having nothing to do with "best quality" it is not subjective... just hard to find data.
Demand declines with price. The HRDX is an expensive amp, if you consider all amps. No way that's it.
I'm still thinking something under $100: Peavey Backstage, Fender Frontman, or the like. Hell, it might even be a Gorilla.