I've dried my own coriander leaf, basil leaf and parsley for "emergencies" but generally use fresh. I probably use more fresh coriander than anything else. Most used spice is chilli powder/flakes (either Thai or Kashmiri).
As GadgetGuy says, it's difficult to buy coriander in small quantities.
Cilantro is also hard to find in small quantities.
I dry my own oregano, and it retains its flavor, and some say it is stronger in flavor. Basil, on the other hand, has never worked out for me when I've dried it. It loses most of its flavor. I assume it is a difference in the amount of natural oils in the two.
I started using dried chilis to make my own chili powder blends a couple years ago, and now that's all I use.
CD