If you want to show a stable and mature image, gray may be more suitable for you, because gray is easier to match other clothes than black. Grey corduroy pants can be matched with different colors of tops, from shallow to deep, making you look more fashionable without being too abrupt.
On the other hand, black corduroy pants show a classic and advanced feeling, especially suitable for formal occasions. Black can be matched with any color coat, which will give people a slender and slim effect.
In a word, whether to choose black or gray corduroy pants should be decided according to your own style and occasion. No matter which color you choose, you should remember to match your coat and shoes reasonably to achieve the best effect.