Echinops have very coarse, thistley foliage. I am not sure how I feel about them in a perennial border. When they are not in bloom they are not ugly, but they do look like a thistle.
Bees seem to be extremely fond of the white ones. When I cut them and put them in buckets, the bees hover around the buckets and will even follow me when I carry the buckets to my car. People like them too, and always ask about them. Whenever some asks me the name of the flower that looks like a disco ball, I always know which one they mean.