Excellent idea. Looking forward to the rest of your rankings.
Agree that Rustic Canyon is awesome--especially for the price. Moorpark CC, just up the road, is of a totally different style. But it's a very fun layout--several forced carries, interesting elevation changes, etc.--and it usually doesn't suffer from the pace-of-play problems that sometimes afflict Rustic Canyon. (Not suggesting it should supplant RC on your list, but it's a bit under-the-radar and worth a visit if you're in the area. In fact, after you finish your top 21 list, I'd love to see your top-21 off-the-radar courses--i.e., courses that don't appear on any of the typical top-100 or best-in-state course rankings.)