Funny, I’ve found erythritol to be the sugar alcohol my system handles best. It allegedly has a glycemic index of 0. Works very well in baking, and has the crystalline structure absent in stevia or Splenda/sucralose. Only problem is that it’s expensive as all get-out.
Isomalt also works, but can have a severe gastrointestinal effect. I believe it to have a glycemic index in the range of 2
Splenda can work as a sweetener, but wouldn’t work right for any sort of baking where you’re depending on the crystals for structure (e.g. chocolate chip cookies.) GI of 0.
Stevia, I find, has a strange flavor. Zero glycemic index. It’s a powder, so it won’t work right in baking.
Maltitol and maltitol syrup are another common sugar alcohol. Their glycemic indices are 50-70 (syrup being higher than plain), but you need more of it than you do of sugar, so you’re getting the same load. Between that and the rip-roaring GI issues, if you have a choice between maltitol and sugar, as in sugar-free chocolate, go for the good stuff.
Xylitol, I believe, is also very low glycemic index. I’ve never used it for any baking myself.
Finally, agave syrup is pretty good as a honey alternative, and has a glycemic index in the 30s. However, I know that some people on here have complained of spectacular spikes from it.
Generally, sugar alcohols are lower GI than sugar, but you might need more of them, and, with the exception of erythritol, can give you gastrointestinal issues.
I have to remember, at some point, to post my low-carb (except for the chocolate chips) chocolate chip cookie recipe. Those were some pretty good cookies . . . .