Sayulita is a zoo. Tons of folks in the water. If you lack for friends, you'll have a bazillion of them there. Also, it's a party town. If that's your thing, it might not be a bad place to stay and you can travel elsewhere if you want more uncrowded waves.
About half an hour away is Punta de Mita, where I lived last Jan-March. Mita itself faces the wrong direction for winter swells, but every once in a while, the angle will be right and it's a fantastic wave, mostly a long, easy peeling right. Lots of longboards in the water, lots of SUPs. Pretty friendly crowd. If you've got a car, a 5-10 min drive from Mita will get you mostly rights at La Lancha and both rights and a good left at Burros. Winter swells hit both those spots. Rent a boat and numerous other options open up.
If you're not a partier, Punta de Mita would probably suit you better than Sayulita. Mita rolls into bed and turns out the lights around 10pm. Seriously. Ain't nothing much happening there. And not a lot of pretty gringas on the beach, either. OTOH, if you're lucky, you'll witness the great local
surf instructor Oso Negro out on a big-ass day with his dog Neptuno on his board. It's really something to watch that dog lean into a bottom turn. Heck, that dog has surfed bigger waves than I ever will. Love that dog. Sigh.
If you'e got any other questions, i'll do my best to answer em.