A 10 GPM, 1/2 HP submersible will give you 10 GPM from about 160'. That is a very common size pump and will easily work on that generator. As to which brand is best, I think they are all crap. They are made to sell, not to last. I use to think Franklin motors were the best, and they may still be. But I have been waiting for 4 weeks just to get Franklin to look at a warranty motor. They use to warranty any motor within reason. Now they put you off forever, and then try to deny a warranty anyway they can. Look for the best price you can get for that size pump, because you will probably have to replace it on a regular basis, no matter what brand it is.