Can you recommend a string winder for a classical guitar?

Even the cheapo ones out of the jar at the music store will do the job. My go-to winder if I don't need a pin puller is an old Herco, though, and I believe it's still made. It has a more substantial handle than the cheapo Dunlops, and the plastic is a bit softer. There's a crosswise slot in the head to accommodate large or small buttons. The large slot measures 28 x 9 mm (not as sloppy a fit as a Dunlop, so you might want to measure your buttons) and the small one fits small vintage steel-string buttons. I find that a good fit on the button makes things easier (and minimizes the chance of hitting the headstock). Mine is rather crudely made but has a nice solid feel.

Planet Waves makes one that incorporates a string clipper, but I haven't tried it.

PS I've been tempted by the one Mikey mentions, it'd make things easier for multiple guitars. You can also buy a winder bit at Stewmac and stick it on a cordless screwdriver.

Again( I do this a lot) I agree totally with jcr.

I think any old string winder would work fine. I use the $2 version from Guitar Center, and they certainly make changing strings easy. I remember when they first started selling those things, What a blessing they were!

Your hands