Tenergy is a small company but they've been making steady gains; not many startups are willing to give well documented datasheets. I've tested a sample of their AA, AAA and 9V LSD and it performs as written, including AH retention in real time, not accelerated aging. But outside the USA, caveat emptor. Add to that, they easily price out most of its competition, like Maha's Imedion or eneloop, while maintaining close functionality.
Back in 2003-4, they were just a vendor, All-Battery.com. Then they went from a rinky-dink address to larger digs at 436 Kato Terrace Fremont, CA 94539 ? ...
Which now happens to be Tenergy Corp HQ. A few years later a sign for Tenergy appeared, following Google street view updated photos over the years; then a power consulting company soon appeared, also housed at the same address.
http://www.manta.com/c/mtx3x7k/standard-engineering-corphttp://www.tenergy.com/http://www.all-battery.com/datasheet/10001_datasheet.pdfAbout 2010, they got themselves BBB certified, which is wholly optional:
http://www.bbb.org/greater-san-francisco/business-reviews/batteries-dry-cell-wholesale-and-manufacturers/all-battery-in-fremont-ca-360907#bbblogoWhich suggest to me, whomever is in charge is working to provide quality services, product I would guess also, and stay in the US for the long haul.
So in the USA, its a good bet for at least the 9V LSD, to which there are few makers.
Tenergy are not exactly known for their stellar QC, however. A more reputable brand like Maha will easily cost $10+. And most reputable brands (like Sanyo) don't even seem to make LSD 9V batteries.