I had to go with Kalashnikov for the same reason others have started from the beginning of this thread. There's something to be said for designing the most common weapon on the planet. And I don't see any other firearm on multiple countries' flags.
A one hit wonder. A great hit but just one.
The gun is on flags because they made so freaking many of them and they are more common than hammers in those war torn country's. Really no different than all the SKS pieces they made and buried, stashed etc.
How does this one gun (except for body count and numbers) match all the other offerings by those other engineering genius's.
You are of course giving your opinion and no knock on that as I am just bringing some facts to the debate.