I prefer writing in the real world, because, as others have said, I can focus on the characters. I do purposely obfuscate the location I'm basing the world on, usually by anonymising the place names and being vague about geospatial relationships (where one place is in relation to another).
Typically though, geography is not as important as the environment. The real world does not describe the feelings and emotions it invokes on its own. During a hot summer's day, the forest is a cool retreat, but on a cold winter's night, it is a dark and foreboding place
That applies whether the forest is on present day Earth, or some distant terraformed colony world. I'd class both places as real, even if neither technically exist.
Once you do start introducing geography, you add an extra layer to the world that needs to be kept internally consistent, but you also add another thing for the reader to have to keep in their head.
Travel writing can also be analogous to the imagined adventures of a fantasy story. They are usually economical with place names, because
a) naming everything and how it relates to everything else detracts from the journey, which is the real story,
b) having fewer names helps the reader build a stronger mental picture of a few key places, rather than many vague outlines, and
c) the authors probably didn't know the names of the places themselves! If you don't know the name when you are actually there, it is clearly irrelevant.