I'm looking for one-word terms to describe someone obsessed with theory and someone obsessed with data. We use the Spanish terms 'teoricón' and 'datoso' which roughly translate to 'theorophile' and 'dataphile' (respectively) but I'm not sure if these are acceptable/clear to native English speakers.
As Dan Bron suggests in his comment above, one common way to express the split between a focus on theory and a focus on data is with theoretical and empirical; others are abstract and concrete, and idea-driven and number-driven.
Though the two words doesn't describe precisely the same split as "obsessed with theory" and "obsessed with data" I also like the contrasting pair noumenalist and phenomenalist. According to Merriam-Webster's Eleventh Collegiate Dictionary the Greek root of noumenon refers to "that which is apprehended by thought" while the root of phenomenon refers to that which appears. However, this pair is not in common use.