MRMDF - usually pale green is much nicer to use and delaminates less. The outer surfaces seem to have a better seal on them and take a paint finish much better. It does cost more but not a lot 25% say?
There are some special screws and matching drill bits for screwing into the edge of MDF - sorry can't remember the make. Whatever you do, don't screw into the edge with out drilling a pilot hole first. Watch out for turbo gold type screws too. The rifling in the threads tears MDF to dust and has very little strength - useless if you have to take a screw out and re-fit for any reason.