I am about to purchase either the Canon 3x lens or the Century wide angle adapter. Which way should I go? Anybody who has used them let me know what you think.

The 3x lens is obviously a much better choice, but the real question is if it worth the extra money for what you need to do?
There is a biiiiig difference in price, which will go a long way in terms of other things you man need to purchase.

I don't think anyone here can advise you which will suit your needs better. You have to decide what you will be filming that will require the wide angle adapter. Remember that the wide angle adapter is not a zoom through converter, and therefor you can only use it on a fixed focul length. It's cheap, but no zooming with it.
If you need to zoom through it, you need a much more expensive zoom through converter or the 3x lens. Between those two, I would spend the extra money on the 3x.
It's also quite possible that you will use it much less than you anticipate, so the wide angle adapter might suit your needs fine.

Hope this helps some.

Century offers adapters/converters that are full zoom through, partial zoom through, and fixed zoom setting. Keep in mind tha people tend to use the term converter and adapter interchangeabily, so check the specs carefully.

The primary optical advantage of the zoom through converter, beyond cost, is that you get the full 16x zoom ratio starting at a wider setting. Other points to ponder are that you add weight while you a good bit of money.

Optical quality of the Cenytury optics is excellent.

I own .7X full zoom through lens adapter, great adapter but it does add noticeable weight to make the camera very front heavy. I would recommend getting the 3X lens. here is a link to a comparison chart for the adapters and the different XL-1 lenses.

http://www.johnbarry.com.au/century/prodv_series/prodv_fitspec.html

I just ordered the fisheye adapter from ZGC. I won't get the full crazy fisheye effect, but if I had the 3X lens, it would give a 115 degree field of view. But I'm still looking forward to using the fisheye, I'll still get a pretty wide effect.

I got the .7X wide adapter as a bonus on a shoot so I saved about $800, comparing the price of the adapter alone and the price of the 3X, just a little more cash and you can get the 3X lens. Then if you got the fisheye adapter later on, you will get that super 115 degree fisheye effect, that's if you ever needed that look.

My two cents: A lot of people complain about the ISII (stock) lens due to the way it focuses, and I believe there are several other issues. The 3x is basically the same lens (right right? please correct me if wrong) minus the image stabilization, and therefore will also have these issues. If you get a zoom through converter, you can purchase a different lens (say, the manual 16x) and get rid of the crappy focus problem, while still maintaining a wide angle. More money, sure, but just my two cents.