No better than them

[Kralizec]

Yet A-H consulted Imperial Germany regarding the situation, issuing their ultimatum to Serbia AFTER receiving a "go ahead" from Germany (and trying to reprise their annexation of Bosnia a few years previously). To be fair, France gave a similar greenlight to Russia. Moreover, the idea of an attack on France had become a mantra. German contingency plans included a mobilization shift toward the East that would have made Prussia virtually invulnerable and would have put France in the difficult role of intervention by aggression against a nation who had not attacked her. Moreover, this would have prevented England from intervening on behalf of France. Germany is no less culpable for WW1 than A-H

To be fair...

I'm a little rusty on the details, but even with AH's disrespectful approach of dealing with Serbia, it's unlikely that Russia would have supported them to the hilt if Austro-Hungary had acted immediately after the asssasination when the whole world was still in shock about what had happened. But they were overly concerned and didn't dare to act without Germany's support.
Russia's decision to back the Serbians was based on a romantic notion of pan-slavism rather than national interest and even if AH wasn't fair in dealing with them, Serbia was still well within their sphere of influence.
As far as I know France didn't particulary care about the fate of the Serbians and the underlying reason for their pact with the Russians was that if Germany went to war with them, France might be able to snatch away Alsace-Lorraine and deliver their revenge for the 1871 humiliation.
Once Germany realised that war with Russia was inevitable despite the Kaiser's honest attempts to defuse the situation, they reached the completely rational conclusion that they either had to attack France first (the Schlieffen plan) or make sure that they stayed uninvolved. Thus they gave the French an ultimatum; wich the French couldn't accept for reasons of pride if not for the reason mentioned above.
I think that these three powers are all equally responsible for WW1. Germany's invasion of Belgium was completely unjust and the British were fully in the right when they declared war even if it was used as a pretext to hide more pressing geopolitical motivations.