There are no "branded" risers, or at least I didn't found one yet
From power point of view the best are molex because they allow 150W power draw, next are 6 pins which allow 75W. Normally a GPU cannot draw more than 75W through the riser.
Currently I am using risers with 6 pins connected via 6 pin cables directly to the PSU, but I am looking to get molex ones. Also I avoid using adapters from let's say 6 pin to molex, or whatever.
Besides this I think a good riser is a one that works