When originally created, Thanos WOULD have lost to Darkseid. Because he was a Darkseid knock off, and needed less power due to the fact that he didn't have to go up agaist PC Superman. However, Thanos has had numerous upgrades since then. He is so much more powerful than he was originally, it's unreal. But, as people are so fond of pointing out around here, Darkseid is the exact same as he has always been. And even though he MIGHT start off stronger, Thanos has the ability to amp up his strenth via cosmic power(which is not agaist the rules of this thread as long as he only uses the power for hand to hand), to unknown levels. That's the difference between Marvel and DC, DC gives their big names a ultra high power level that doesn't change, where as Marvel starts their big names at a lower level, and then gives them the ability to become more powerful when they need to. So Thanos FTW.