Bottled water: Distilled vs 'Purified Drinking' water?

I've done a fair amount of research into the chemicals dumped into municipal tap water. Did you know that fluoride is actually a harmful chemical? Yep. AND has not been conclusively proven to strengthen tooth enamel. But, all the water filtering jugs n such (ie Brita and Pur for a couple) say they remove 'most chlorine, but leave the beneficial levels of fluoride'. I come from well-water upbringing, (best water on earth!!), but now have city water. My cat is licking her fur and chewing like her skin is bothering her... and this has started since I switched her from Reverse-Osmosis water from the ranch in CA to the city water here in SC. I'm poor (read BROKE), but I can afford a big jug of water if it'll help her feel better. So... Distilled? or 'purified drinking water. What's your opinion?