This is difficult to answer. IMHO the The Down Low Glow theoretically should be visible from more angles. In practice I think that DLG could be washed out easily by other lights in urban areas. The Monkey Lights on the other hand might not be as visible from as many angles but may be visible more often fromt the angles that both the DLG and ML are visible. I think the movement of the ML would be more eye catching.

That is just my impression bit I have seen neither in person. I am just going from the videos that I have viewed and trying to judge by the nature of the lights. So I would choose the Monkey Light if I could only have one.

My riding buddies call me Dwight the Light so my opinion is highly valued when it comes to lights because I research them so much. You might be able to do a search and find a thread where someone has seen both in person.