Quest bars are soy free. They are sweetened with stevia (which I avoid since reading about a study on rats whose fertility was affected by stevia).
I think Honey Stinger bars are soy free, but not as low calorie and not as high protein as I'd love.
Simply Protein Whey bars are good too, and not sweetened with any of the sweeteners I try to avoid (stevia, sucralose, aspartame, etc...)
Caveat - when I went looking for "soy free" I decided to be satisfied with bars that don't have soy PROTEIN in them. I have decided a while ago to be ok with soy lecithin (I don't have an allergy, just want to avoid large amounts of soy). So I don't remember if these 3 have soy lecithin in them or not.