I think that discussing only this 2 dimensions of one's personality leads to a very limited discussion.

A great programmer with incrementalist tendency in his perspectives can get a lot done in a short time, but also a great programmer with a completionist perspective can make solid work and can do it in a way that re can really finish things.

My opinion is that most code has a brief life, so spending too much time in a code that will be thrown away in 6 months isn't going to get you anywhere. You need a very good sense of what's important, what's the heart of your application, and make it as good as any completionist would dream of. In the other hand keep an incrementalist aproach to the everything else, and if it's really good and people really use it can always be improved.

PS: Useless: just noticed this huge gap between comments, from early 2005 to mid 2007