The Newsweek polls are fairly awful. Gallup's are really bad right now because of how heavily they are weighting democrats in their surveys. I think PPP and Rasmussen Reports are pretty good.
I have completed a detailed analysis of the internals of two dozen major national pollsters, and have found the following:
BTW, you are correct that the Newsweek polls (Princeton Associates) are extremely biased.
What is interesting is that PPP and NPR polls are run by Democrat pollsters (NPR by Clinton's pollster)