There is no "being incrementalist is better than being completionist". Your project will be lost if you don't have both and even more if you don't have both talking to each other.

Its no question: the incrementalists will do the quick fixes that a client might need NOW. Thus incrementalists usually work on small chuncks of the code but on chunks that are spread all over the project. Thus they usually achieve a better overview over the whole codebase.

In an ideal world there must be frequent sessions where all coders (and quality assurance guys) go through the quick fixes and find out which ones need a broader and more detailed rework. This cannot be done with all quick fixes unless you have 10 times more completionists than incrementalists.

So good projects have an incremetalist at the coding front and some hopefully very bright completionists in the offices behind.

Well, for me as a more completionist thinker its hard to place me in the backoffice. But life seems to be like that. Life rewards action and speed. It simply sells better, if you can shout "done!". Your newly introduced bugs give you the chance to shout "done!" even more frequently. Managers love this. Its easy enough for them to understand.