I can highly recommend, a capri 14.2 (although it isn't an EASY boat to sail).. the 16.5 is good too. Holder 14, Vagabond 14.. and they should be cheap to find.
Other boats to consider, Lido 14, Omega 14, Designers Choice...
Keep in mind each of these boats will be hard to learn on, and generally tender. But they'll teach you to sail faster than many boats a lot bigger.