I own a Porter Cable finish nailer and bought it because of recommendations from professionals who use theirs daily. If you take care of it, you may never need to buy another finish nailer again. I've owned my now for 5 years and have never had a single problem with it. The only other nailer that I've seen better rankings of is the Paslode...but you'll pay a premium for it. I'm pretty sure I bought my Porter Cable from Amazon.
As for Harbor Freight, my dad likes to buy things from there becuase it is cheap, but he ends up buying the same tool every couple years. I can't convinve him to spend the money on a good tool and quit buying the cheap stuff from Harbor Freight. I recommend buying a good tool and then taking care of it so you don't have to replace it for a very long time.