I use a large ATX case- Cooler Master ATCS 840:
I chose this because it is easy to work on due to the size and the fact that the mobo tray slides out.
As you can see from the vid it comes with 3 230mm fans and a 120mm fan.
In addition to this I have added 6 optional 120mm fans- three intakes on the HDD cage and one at the back drawing air off the GPU.
With regard to fans I am using Akasa Apache, Noctua and Sharkoon Silent Eagle fans. All these are virtually silent in operation and the Sharkoons in particular shift a lot of air.
It is worth buying good fans as they cost about the same as crap ones.
The number of fans you need depends on whether your case operates on negative or positive air pressure and also what you are putting in it.
If you are overclocking you may need extra fans depending on the design of your case.
You might also consider one of the self contained water cooling units such as the Corsair H50.
At a push I would say the Sharkoon fans are the best.
hope this helps, John