The most popular cover color at Quo Vadis is black, too. It makes a certain amount of sense: black is the businessperson’s color of choice, and many of us use our planners to keep track of work-related items. And, hey, black goes with everything.
On the other hand, there are so many lovely colors to choose from! I’ve recently converted to the new Robert le Hros series (I use the blue University #28 pocket agenda to keep track of my appointments), and I love its bright colors and whimsical pattern. And because like most New Yorkers I’ve already got way too much black in my wardrobe, I don’t have to worry about it clashing.