That's a very good question you have raised for which there's no correct answer. Nowadays PSU manufacturers first introduces a model, send it for review and when there's some good review floats around and they make some good sell they just silently changes some internal components to cut cost. Thus we get some lower quality psus which were higher of quality before. Often such psus gets a new revision number and often does not. Now which PSU manufacturer will do such act for which PSU models is mighty hard to tell.
On the plus side a new revision generally corrects the flaws of the previous revision and adds some little improvements. As a rule of thumb getting a higher model of a decent PSU manufacturer is always the safest bet or try to look for the OEM of a psu modem. If it's from a good OEM the build quality is also going to be nice. Another way is to look for feedback about a particular PSU of different forums if you have doubts.