I would think that most fantasy maps use aspects of both. They're made to most accurately display any information that is critical. The work to get an absolute perfect representation of a fictitious place, though, is probably astounding. So some things are sacrificed to make the completion of the job more realistic. How much is sacrificed and how much is preserved is up to the individual, as you pointed out, but I think that by and large most fantasy maps are a mix of the two approaches. Interesting topic!