I prefer to use a hot chocolate mix that has: 1) no dairy, and 2) sugar-substitute. It IS possible to get some dairy-free hot chocolate mixes. But it's just as easy to make your own hot chocolate, since most recipes call for just:

cocoa powder sugar milk vanilla extract pinch of salt

[1] [2] [3]

If you're making a mix, you'll want to make vanilla sugar first. There are three ways to do this:

1. buy real vanilla powder, stir into sugar
2. buy real vanilla beans, and let it sit in sugar for a week or two
3. buy synthetic vanilla extract, mix with sugar, and then dry the sugar mixture

Real vanilla is fairly expensive (and doesn't make a noticeable difference), so I prefer option #3.