Except for one*, I've never met a color I didn't like, however, mustard yellow and bright orange are pretty low on the list. They do occasionally have their "aha!" moments, though. I particularly love working with black. It really makes other colors POP! I love pink, too (might be because it's my favorite color). :mrgreen:
*The one color I don't like is solid white. I guess it's because white can be persnickety about showing the seam allowances underneath it if you happen to get them ironed the wrong way ... and also because it seems to get dirty so easily.