Ground cinnamon is an extremely common ingredient, but it can get super fancy, with some varieties being sourced from Vietnam. These varieties cost more than their generic counterparts, and it's hard to know if they're worth the money. Photo by Evelyn Giggles.
To figure out if fancy cinnamon is worth the extra cash, Cook's Illustrated tried eight different varieties (half from Vietnam and half of unspecified origin). These were then tested by being "stirred into chilled rice pudding, baked into cinnamon rolls, and sprinkled and baked on cinnamon-sugar pita chips".
It turns out that there is a noticeable difference between cinnamon varieties, but only in "raw" applications:
Tasters felt the burn of many of the Vietnamese cinnamons when tasting them sprinkled on rice pudding, but that heat all but disappeared when we sampled the cinnamons baked into cinnamon rolls and on pita chips. In fact, tasters struggled to detect differences of any kind in these baked items, deeming every product acceptable except for one outlier (more on that in a minute).
In short: If you're baking, pretty much any cinnamon will do, as cinnamaldehyde -- the compound mainly responsible for cinnamon's spicy flavour -- is extremely unstable in the presence of heat. If you are going to be sprinkling it on rice pudding or some other cold food or beverage, choosing the "right" cinnamon is really a matter of personal preference. If you like "a big, spicy flavour", Cook's Illustrated recommends Penzeys Vietnamese Cinnamon Ground, but if you like a milder, sweeter flavour, Morton & Bassett Spices Ground Cinnamon is a your best bet, with "a tempered heat and a complex bouquet of floral, woodsy and earthy aromas".
Shopping for Cinnamon [Cook's Illustrated]