I don't mean to be too specific, but I would go for the Hobie 16. Lots of fleets for racing, almost everyone knows the boat so you can get good advice from a wide range of people, tons of used parts for fair prices, and they are a pretty solid boat for rec sailing. You can also get a decent one for around $1000 in most of the country. When it comes time to upgrade to a newer or larger cat, you can also sell it for around $1000. They are very easy to single hand. I have sailed them with total crew weight of about 450lbs in heavy air.

Check out the forum on the Hobie cat website, Hobiecat Forum, for more information about the boat and to see if there is a fleet in your area.