It depends. In the U.K. biscuits are dry and crunchy. We call them "cookies" in the U.S. In the U.S., biscuits are often described as "soft and flaky" or "light and fluffy".

Crisp is better to use here, because "crisp" can be used specifically to describe the pleasing firmness of food. Eg: crisp lettuce, crisp bacon, crisp apples. "Crisp" is a combination of firmness + taste. \ Crunchy generally refers to the noise food makes when bitten. The "crunchy potato chips" / "the potato chips were crunchy." It refers to a physical state of food.