Maltitol

Taste good, but gives me the worst gas.

As far as taste is concerned, anything containing this (helped along with sorbitol) doesn't seem different from the real thing. I've tasted some sugarless chocolate sandwich cookies once that had these sweeteners in them; they're so sweet, one could almost swear they cheated and put sugar in it -- but they didn't. However, this is not listed among the five approved by FDA. Malitol doesn't seem to be available to the general public (for use in cooking, and so forth). I see it listed among the ingredients in various sugarless products, but never by itself. Therefore, I cannot give this any higher than a three at this time.