I don't know what all is in sweet potatoes, but I've been eating them a lot more lately (baked), and good things have been happening that directly coincide with my sweet potato consumption. I was initially doing it for the beta carotene, and since you can eat the skins without worry of toxins (regular potatoes can have trace to high levels of toxins there), but it seems that my mouth health improves greatly when I eat them (it feels/smells much less bacterial and more clean), my fatigue lowers, and my mental/neural function seems to improve considerably.
Of course, I can't say this stuff really is because of the sweet potatoes, nor that it would work for anyone else, but I can suggest that you do studies on it. It seems like they're a super food to me. At the very least, they're chalk full of beta carotene and sweetness.
I notice the most improvement when I eat two large sweet potatoes in a day (the improvement seems to last quite a while, too, and doesn't wear off abruptly, either). Maybe if I just ate one a day but did it every day, that would do it, too.
As for taste, they taste best to me when they're baked for a long time, until they're very soft, especially if I add butter. The big fat ones I might bake on 450° F. For an hour and twenty plus minutes, but the thinner ones don't need nearly as much baking time. I should cut those fat ones in quarters. Butter improves the taste (and should help the beta carotene conversion to vitamin A).
Even the whole sweet potatoes drop sticky juice/molasses during the baking process; so, I bake them on a cast-iron pan or something.