@uberbatman I think there is sufficient archeological evidence to suggest that Neanderthals were smarter than modern humans. Aside from the larger brain capacity they developed more advanced stone tools and were the first to bury their dead, which would seem to indicate they were more advanced from both technological and social perspectives.
Of course nobody knows why they failed to survive. There are several theories. One of these is absorption. This theory basically holds that they simply became a part of the modern human genome through inter breeding. Genetic evidence supports this in that around 4% of the DNA of some populations is Neanderthal.
Another interesting theory is that although they were smarter, because of the construction of their larynx they had less capacity to vocalize, which limited their linguistic capability. You can make up for the fact that you can utter fewer sounds by developing richer syntactic rules. However, expression of complex ideas becomes a much lengthier proposition.The language theory holds that they died out because they were less able to share information even though they were smarter.