a 16" and 20" would be only equal if the roads are perfect I find. BUT if you have typical roads with lots of cracks and potholes then the ride between the two would be huge, with the 20" being the much better ride. This is from experience because I own a 26" bike 20" bike and a 14" tire size folder and commute daily with them swapping rides often for fun. on my commute there's sections that are just feeling like cobbles and with my 20" I already feel like it slows down due to the wheel size angle of attack. While with my 26" I barely feel any slowdown as it floats over pretty much all of it without a hiccup. Forget about the 14" with that I just try to avoid it all together. Also the tires I'm using for the 20" is schwalbe surpreme in the front and big apple in the rear, while the 26" is on fat franks, the bike accelerates like a slow truck but once it gets moving it's nice.

I would only choose a 16" wheelsize if space is a concern on where you need to park it or where you are taking it through.