If you can go with a higher brand name and cannot find the VFC, I would recommend either the SRC Gen III 416 or the Top Tech 418. The Top Tech 418 has more reviews, and blowback, while the SRC Gen3 doesn't have very many reviews (if any at all) and the only place I could find them is evike, but they are also cheaper.
For lower end I would recommend the AGM if you can find them in stock because they are fully metal outside and inside, however AGM isn't coming back until Q4 of 2010 since they got shut down by big bad PRC airsoft gun and fun obliteration squad. Other than that on the low end I have heard good things about the Dboys, full trades, full metal, etc.