In actuality, there are only a few manufacturers of LiPo cells around the world.
AFAIK, the best ones come from korea, from what i've read.
Hobby king doesn't own the factory that makes Zippy batteries, they own the factory that makes Turnigy batteries. If you look, the Turnigy packs cost even less than the Zippy's for this reason.
HK purchases Zippy, Rhino (also made by Zippy), and Polyquest from outside sources, which put the Zippy (or whatever brand) on the packs for them.
I have read in different threads, not sure if it's actual fact, that there aren't any LiPo manufacturers in USA, that all packs are purchased from overseas manufacturers, and the brand names are put on here. As I said, I haven't researched this myself, and am not stating it as fact, but it's what i've read. If this is true, you might just be buying FP or TP packs at very high prices that have the same cells in them as some cheaper packs.
I have Zippy, Rhino, Turnigy, Thunder Power, Flight Power, and E-flite batteries, and I can honestly tell you, from my experience, that the E-flite pack seems to be the worst as far as longevity. I have a Thunder Power 3S 1800ma 20C pack, that after about 20 cycles, now takes over 1 1/2 hours to balance charge at 1C. I don't push my packs to LVC, and the Blade 400 I use that pack in doesn't draw enough current to overdraw that pack (all I do is hover it right now), so it's not user error.
I have a few Zippy 3S packs, that after 1 year of hard use, don't have the discharge capacity they once did, but I have Rhino's that do, even after the same amount of use.
The Jury is still out on the Turnigy brand, as I don't have enough flights on them to give a real world opinion.
My Flight Power pack is a 3S 2550ma, and is still going strong after 1 year.