Depends on the time frame you are looking at. If you were looking at companies that have good prospects for say, a ten year hold then all three (MRX, TARO, and CHTT) have good prospects. I would probably pick TARO over CHTT. Since they are all smaller niche players they always have the risk of competition but they seem to be pretty well established in their areas and all three have OTC products that sell well and those are less likely to be displaced.
they are all taking a risk that there will not be any structural changes in the derm market. the abstracts from the amer soc of derm and other meetings suggest there is a quiet revolution going on. So I think they will be good shorts in the distant time horizon: 2 years or so.
Of course we could all be good shorts in the 2 year time horizon