Caulking Help!

Ok my project for the week is to re-silicone the tub where the tub meets the wall. This will be the third time in four years! My question is, what is the best caulk/silicone to use? Last time I used GE’s Silicone II, white. It states its “Mold & Mildew Resistant”. Obviously this is not the case! Also is there a better caulk/silicone for hard-water?