US universities are far better than Europian Universites. Normally, in US it takes five years but if you compare the quality to the universities of other  countries, it is almost five times stronger. If you look world renound journal- like Nature, Science, JACK, Angewandte Chemie, you find most of the article from US Universities.  Ph.D. is all about research and publication.

I am also doing Ph.D. in chemistry in USA