I can't say enough good things about erythritol, an alcohol sugar that, unlike other sugar substitutes, is actually sweet and doesn't have a weird "off" flavor (although only 60% as sweet as table sugar by volume). Its glycemic index is zero, it's completely inert, and the only way it interacts with your body is to tell your taste buds they're experiencing sweetness.

I use it mainly in coffee, which I like sweet. It's fine for baking too. It looks like sugar, although the size of the crystals vary by brand. The brand I find totally sugar-like, texture-wise, is ZSweet.

It has two downsides. It's pricey ($15 for enough to fill my smallish sugar decanter 2.5 times) and being a larger molecule than table sugar, it can cause some people mild intestinal distress, or so I'm told. Happily, it doesn't do that to me.

If your gut tolerates it and you can afford it, it's wonderful stuff.

@mordant I'll look for that at the store. Perhaps I can afford it; I can give it a try, anyway. I'll add that to my grocery list for tomorrow.