I'm guessing you actually meant 1900g, because, well, a 2900g wheelset would make an excellent downhill MTB wheelset.

It would depend on how aero the 5 spoke is (probably not real aero, those are relatively old design probably), and how fast you ride, and how steep the road is.

Too many variables to just say "aero is better". If you're climbing a 10% mountain, then light is better unless you're going really, really fast, but it also depends on how much lighter, and how much more aero, etc.