The geologists who have most impressed me during my career have been those who created their own niche in science. Some mapped whole regions and became the expert to consult for that area; some opened new fields to view for others to follow; some wrote textbooks in such clear and inspiring language that their words became internalized in me. All were great observers. And all of these geologists were also great teachers, able to impart their knowledge clearly to others. A few examples: Robert Compton, field geologist and author of textbooks on field geology; Adolf Seilacher, paleontologist and founder of the modern paradigm of ichnology; Robert Frey, ichnologist and editor of the first textbook on ichnology.
...I remember an insightful talk comparing the accomplishments of Charles Darwin and Alexander von Humboldt, both with a geologist-turned-into-a- biologist-vita and impressive fieldwork campaigns: Darwin had the ability, drive and focus to infer something deep from his observations, and, among others, formulate his descendance theory whereas Humboldt - depite his pioneering work in many fields - is arguably lacking an accomplishment of similar importance. Thus, I daresay that doing fieldwork is (perhaps necessary but) not sufficient to achieve something great in geology.
It is hard to say which one is the best, as they both contribute to the advancement and application of geology in different ways. Some people may prefer one type over the other based on their personal interests, goals, and values
Field geology is very important to know the exposed geological phenomena in the field. On the surface, such as folds, faults, stratigraphy marks, etc., they are considered a geological tool, and therefore they are converted into a geological map and interpreted.