gensacearespammers are consistently ranked highest among the battery geeks over at another site, and I mean battery geeks. They rank right up there with TP and Max amps packs. As Lloyd said, the Turnigy packs (nano tech's specifically) have been great too. The others, not so much for me. Helis place a lot of demand on packs in a short period of time as many choose to run at 100% throttle (at least I fly in IU mode anyway, for many reasons) once your airborne and flip the switch. Packs that can't keep up are discovered in short order.