Neither, from a real-world performance point of view; your wallet may disagree. Or maybe the 16' one, since it's longer.
There are two main kinds of HDMI cables
: those which are certified for Standard Speed, and those which are certified for High Speed. (Actually, three kinds: Standard, High Speed, and Totally Not Certified At All.) But just because a cable is not certified High Speed, or not certified at all, does not mean that it won't work with 3D.
Both Monster Cables are listed in fine print as "Ultimate-high speed rated" on their website. (The word "Ultimate", along with the entire rest of the webpages, is a bunch of marketing bs.) So I think we can conclude that both cables, at least at some unspecified-by-Monster-length, pass HDMI high-speed certification. Unless Monster is lying about that. Because when a company sues another business simply because that other business is named "Monster Mini-Golf", what won't they and their army of zombie lawyers do?
See the BlueJeansCable website
for some non-snake-oil information.