If you are looking for good windsurfing as well as an active night-life go to Gran Canaria. Most of the good spots are north of Bahía Feliz so that's a good place for living. When you talk about windsurfing in Gran Canaria it's impossible not to mention Pozo Izquierdo. After all Pozo is where Bjorn Dunckerbeck learned to sail. Going up the coast from Bahía Feliz you can choose from a number of good spots: Playa del Aguila, Pozo Izquierdo, Mosca Point, Arinaga, Vargas and Ojos de Garza, to mention a few. You'll get the best winds in the summer and a 4.7 is the biggest useful sail. In the summer you'll probably be best in the range of 3.0 to 3.5 - like I said, the summer is windy! In the winter winds aren't as good but waves get better. The locals say that you can sail every day of the year if you have a car and you know where to go! Most of the windsurfing beaches are rocky so launching and coming in can be tricky if you don't want to damage your fin. If you are a novice avoid Gran Canaria in the summer or stick to watching - the winds are way too strong.
Pozo is easy to find. Going north on the highway take the El Doctoral exit and turn to Vecindardio. Then just follow the signs. In the summer this beach has the best waves of the island. Morning wind is usually off-shore and you can get a pretty good angle for jumps. In the afternoon the wind often turns to side/on-shore. The morning off-shore can be a little gusty and the waves sometimes weaken the wind near the shore. In the spring the waves can be better at the near-by Mosca Point, but Pozo is the homebeach of Bjorn Dunckerbeck and is the island's World Cup host.
A couple of kilometers north of Pozo is Arinaga. Here the wind is almost always off-shore and the water is smooth if you don't go very far out. Arinaga is best suited for slalom but it's pretty hard to find. You have to drive through an industrial area to get to the beach and mostly it's not worth the hassle.
Vargas is a big bay with a lot of room for windsurfers. But you want to avoid the southern part of the bay because of the current, which is especially strong during low tide. The wind is pretty steady, sometimes as good as Pozo and the waves can be anything from bump'n'jump to 10 feet. The most important thing to remember about Vargas is the current - if you are not sure of your skills don't sail there.
Ojos de Garza
If Pozo gets too rough you might want to try Ojos de Garza. It's a sandy beach so launching is easy for your feet but the beach is also sheltered from wind which picks up the further out you go.
Playa de Aguila
If you want to sail next to your hotel you can try Playa de Aguila which is right next to Bahía Feliz. I recommend the other spots though. In the winter the island often shelters the beach from wind.