there is no standard in C ratings so don't trust them, the only effective way to mesure the quality of a lipo is the internal resistance


go for a brand that uses known cells if you can, gens ace are good for the price, not the best on the market of course but they do the job as well as high C rated nanotechs, the best being enerland and kokam -speaking about the cells here-

typically a 25C rated gens ace will provide more amps than many other brands, I'm using them with my RX8 with no problem. I used many 25C hyperion lipos too in the past with no troubles either. The highest your voltage is the lowest C rating you'll need