For Nickel based batteries, it's Sanyo all the way. They are significantly more expensive than the competition, but the quality is fairly obvious. They don't self discharge as quickly, they deliver more voltage under load, and they last longer. I realized the difference when I replaced my starter pack. I had built it out of Turnigy's first to be cheap, and it would hold a charge for about a week. The batteries had noticeably degraded in performance after about a year. I made a new one with Sanyos, and I have gone 3 weeks before with no noticeable self-discharge and it is still going strong after a year. The starter has more power too with the same cell type and voltage.