Since the fields you mentioned (quantitative marketing and finance) are both heavily based on mathematics, I would think that the quantitative score is by far the most important. If you can possibly avoid it, you don't want to be in a position of having to explain away a weakness, especially where the weakness is at a very important criterion.
Thus, I recommend that you submit only the GRE score and make no mention of the GMAT. Although your verbal score in GMAT was quite good, it isn't quite as important for those fields you are applying for, and the mediocre quantitative results would probably outweigh anything positive you might otherwise have.
That said, you could simply call the schools you want to apply to and ask them directly; since each school might have different preferences for GMAT and GRE and their respective scores, one blanket answer might not be suitable for all the schools you are applying to.
Specifically, you could try to talk to the department chair or to the graduate program director (just call the department office and ask to be transferred to the right person). You don't have to identify yourself; just say that you want to anonymously ask a question related to admissions.
I know that that last suggestion might sound wild, but believe it or not, it often works surprisingly well--I recently used that kind of strategy to receive anonymous answers from a research ethics office concerning a grey research ethics question I was faced with, and I quickly got the exact clarity that I needed for my situation. Never underestimate the power of picking up the phone and calling.