My take on sweetener is this, sugar is hardly a necessary food group. If I'm sweetening something it is probably a treat rather than a staple.
Fructose does not have the same impact on blood sugar as glucose as it does not require insulin, you may want to consider using that instead of sugar. however, fructose has other disavantages as th eliver turns it in to triglicerides.
As far as the other sweeteners go, harm is a relative thing. I'm willing to risk a bit of the trots as it is something I do infrequently and I'm not using that much.
Different sweeteners have different aftertastes and some say that Splenda goes best with tart recipies. I use Perfect Sweet (xylitol) and Splenda and am considering Zsweet.
If you are making a cake, I'd be more concerned about using wheat flour than the sweetener :?
I have developed a few sweet low carb treats - I get carb cravings at certain times of the month. I have a low carb chocolate cake using ground almonds, a mascapone cheese based coffee dessert and a chocolate dessert, things with berries and cream and greek yoghurt, and most recently a baked lemon custard macaroon tart
I have also experimented with chococlate and M&S Dark Swiss has relatively few carbs for a chocolate, as does G&B dark, both are around 70% cocoa solids.