The Powerflo II isn't a bad pump and since it works for you, it wouldn't be a bad idea to replace it with a like model. There are other alternatives depending on your objective. If you are trying to lower energy costs, which should already be pretty low with that pump, you could go with a two speed pump but you would need to get a slightly larger pump to get the lower speed. Running at lower speed saves energy costs and may improve filtering some but usually at the expense of skimming ability because of the lower flow rates. So there are some trade offs.

As for manufactures, many pros think that Pentair makes a more reliable pump than Hayward but most of the opinions seem to be perception rather than reality so it is hard to tell if one is actually better than another. From what I can tell, both manufactures use A.O.Smith motors for most of their pumps so the motors should have the same reliability. But it is possible that they may use different seals which could explain some of the reliability issues.