There are two common sweeteners that work well as a direct substitute for honey. Honey is about 82% simple sugars (by mass).
- Maple syrup is about 60% simple sugars, making it slightly less sweet than honey. It has a distinctive flavour that although different from honey is quite pleasant. Maple syrup is a good choice for Canadians and Americans who prefer to buy relatively local products.
- Agave syrup is produced from the sap of the agave plant and is about 70% simple sugar, putting it close to both maple syrup and honey. The plant is native to the southeastern United States and Mexico.
If skipping honey because of ethical concern for bees, it's probably best to avoid fruit-based substitutes that might be labelled as "vegan bee-free honey". Those are often made from apple juice, and honeybees are often carted around for thousands of miles to provide pollination service. There's nothing inherently wrong with apple production, it's just that the current practice of using honeybees to pollinate apple orchards means that bees are equally implicated in either honey or "vegan bee-free honey" based on apple juice.
For people who prefer less-processed/less-refined foods, date paste made by soaking and blending dates is a another good alternative, though slightly more labour intensive and probably not commonly used for tea.
I've only listed the most common sweeteners here, there are even more if you want more options.