I personally use Blue, I love hearing the super loud clicky noise while I type!
Red: Linear, smooth, quiet, low actuation force, popular for gaming.
Blue: Tactile and clicky, loud, higher actuation force, favored by typists.
Brown: Tactile but not clicky, moderate actuation force, good for both typing and gaming.
Black: Linear, heavier actuation force, precise, good for gaming and accuracy.
Yellow: Linear, fast, low actuation force, designed for competitive gaming.