Depending where your textured models is going, you might not need AO bake in the diffuse. FOR PBM, I barelly put AO and remove shading from the texture. This model you showing has a good lighting and specular, and this is why it look good. Add some sharpen to your diffuse maybe? Is really hard to say with no sample of your…
Here are my diffuse, normal, ao and render of barrel. Also normal looks weird, did it in xnormal, strange. Tell me please where I should make my improvements