Goro is more referring to the way that it's looked at from the perspective of a medical student applying for residency. All research is able to be used - and is weighted close to equal - in the evaluation of medical students for residencies. You would have a competitive advantage applying for specialties in medical school if you focused your undergraduate research accordingly, if that's something you actually wanted to do.
My understanding, for medical school admissions, is that it doesn't really matter. Do something where you can be involved. Above all else, admissions like to see independence. Being seventeenth author on a paper means nothing, but giving a poster or an oral presentation which you, presumably, have taken the lead on, is a big deal.
I see. Thank you for clearing that up. I think I would surely learn more if I were to do basic science since clinical research (at least what I have done previously) is mostly centered around data and crunching numbers. At the same time, I think it's great to be exposed to clinical/medical research, however, since it's what you'd be doing in medical school from what I have heard.
For med school admissions, all we care about is that you have learned something about the scientific method, even if it means you studied flatworms in mexico.