Stardust wins. I believe that Star Dust is stronger than Beta Ray, as Ray needed a buff in order to be effective against Asteros, while Stardust didn't get any amp I recall (name might be wrong there, sorry).
Beta Ray Bill = Thor Thor = Superman Superman = Manhunter Thusly, Beta Ray = Manhunter Beta Ray Bill = Stardust Regular Beta Ray < Stardust Regular Beta Ray = Manhunter Manhunter < Stardust.
I understand that most of these ='s are debatable, however they are all relatively close in power; with the only truly significant difference being their different sets. Law of Syllogism ftw.