Jeff emails: The Litvaks were not more “rational” than the Chassidim, in fact, the Gra and R. Haim were major league Kabbalists, the Gra wrote more on Kabbala than he did on Talmud, and we have R. Haim Brisker’s kavvanot hatefila extant. In fact, there’s a famous story about the time the Alter Rebbe was to meet the Gra, and he famously said that he wasn’t afraid of the Gra on halacha, but on sod (Kabbala). It was the Gra who brought back Luzzatto, for example, still strong in Litvak circles, and a more heavy duty mystic than that we do not have in the Jewish tradition.
The Rambam also is not more “rational”, rather, he was a Rationalist, which means a different thing, it means that he believed one could understand Gd by use of the mind. The idea of Judaism as “rational” in the common usage comes from Mendelsohnn, in his polemic in favor of Judaism in Germany.