What kind of rider are you? Are you one of those people that go to a bike store, look at a couple models and buy it without:
a) getting it fitted
b) going for a test ride or two
?
As you probably know, a lot of the people who get bikes without knowing the market tend to buy one, ride it a couple times and let it rust in the garage.
IMO the only three manufacturers you should be considering are Brompton, Dahon, and Bike Friday. If money isn't a factor, check out Moulton.
If you're strapped for cash, Dahon has some decent low-end to mid-range models - it's been a while since I last checked them out, but I think the Curve, Mu, and TR series tend to be pretty decent. The flip side is they tend to be kind of heavy and bulky folding-wise, and build quality can be kind of dubious. Also their bike parts are custom so you'll probably have to go through their supplier to get them. Dahon is considered the giant of the folding market; most bike stores should be able to help you out with a selection and finding what works for you. They may have a 16"-wheel model, but most of their stuff is aimed at the 20" and higher crowd.
Bromptons are well-made, there is no doubt about that. If you want a functional, super-compact bike that you can take with you on most public transportation, consider Brompton. I don't have one but everyone I've talked to who has one has been happy with it. They have small/medium/large sizes and prices tend to be like $1,000 and up.
Bike Friday is the third company you should be considering. Now, I'm biased toward them because I own one but I'll give you as much unbiased info as I can. They're an American company based out of Oregon that makes custom bikes with off-the-shelf parts, meaning you can exchange and replace existing stuff with just about anything. Wheel sizes are mostly 20", with their "Tikit" commuter model consisting of 16". If you know your sizing (from riding road bikes, etc), you can send them your info and they will build a bike specifically for your dimensions, riding style, etc. Fridays are the closest thing to riding a "full-size" bike while still having the functionality and usefulness as a folder. They tend to use Shimano's Capreo system (built specifically for folders, trikes and recumbents) with 53-tooth chain rings to give gear ratios similar to bikes with larger wheels. If you know of a local bike store that sells 'bents or trikes, chances are they'll also sell Fridays so you can get test rides.
Also if you're really interested check out the folding bike subforum on Bikeforums.net - there are a lot of knowledgable people there who are happy to help.