Concrete.??....

[MESSMAKER]

Ten different people, ten different suggestions. That is how concrete seems to work. I think that this boils down to the fact that you can get good results several different ways. A good base that does not collect watter is a good start. I have seen rebar,mesh or fiber used and it all seems to work. A little stronger concrete with mesh in it is the easiest and probably the cheapest choice, but it is up to you.

 

[Mace Canute]

Yes, lots of differing suggestions, but they are all good ones.
MichiganIron's comment about the amount of water in the mix is more important than you might think. The amount of water used to mix the ingredients is by far the most important factor in determining the final strength of the concrete.
A quick Google search for "amount of water in concrete" gives several informative sites that explain the making of concrete very well. Concrete: Scientific Principles was the very first hit and it has much to say about the matter. Several sites on the same page are very informative as well such as Appendix J: Tips for working with concrete where they talk about Concrete Reinforcement amongst other things.
"Concrete can be made much stronger by reinforcing it with steel rods (rebar or rerod) that are embedded in the concrete. Reinforced concrete should be at least 7.5 cm thick. Rerod should take up 0.5% to 1% of the cross-sectional area. The rebar should be placed within the concrete form and be located at least 2 cm from the edge of the form. It should be placed in a grid pattern so that there is never more than 3 times the final concrete thickness between adjacent rods. (With a final thickness of 10 cm use a grid spacing of 25 cm). All intersections where rods cross should be tied with wire. The proper space from the bottom of the pour in a slab is one third the height of the final thickness. It can be achieved by setting the rod grid on a few small stones before the concrete is poured or simply pulling the rebar grid a couple of centimeters up into the concrete after some concrete has been spread over the whole pour.
There's quite a bit of information in those sites and they are well worth the time spent reading them if you have questions about concrete.