I think ideally, no sweeteners of any kind.
If weaning off sugar is a deal-breaker or a favorite treat-recipe requires a sweetener, then stevia seems to be the preferred artificial option and honey/maple syrup the best natural ones. All used sparingly.
I've hardly sweetened anything since I started this. I've made the chocolate baked custard from the PB cookbook and added maple syrup to that. I get small amounts of sugar from very dark chocolate.