Here the situation: Both the german empire and the HRE were relatively decentralized states if compared to others like Russia or France, with the second Reich being a federal monarchy and the HRE a chaotic administrative inferno of 100 billion duchies, kingdoms, counties and anything else loosely united.
Based on that, let's say that the HRE could be centralized to the same extent as the german empire, and so between a austrian led HRE and the OTL second reich, which one would be better for the germanic people's in general and the others, like the hungarians in the HRE and the sorbs in the IInd Reich?