A good top is a melamine kitchen counter top. You can either buy them new, or look for a kitchen supplier near you and ask if they have any they removed during renovation, and these are often free. They are thick, quite cut resistant and you do not really worry if you cut or burn the top surface in use.
Using plywood works well, and I just left it unfinished, so that when it gets too scruffy I can just use a sander and get it looking reasonable again. Using plywood for shelves is also good, it is a lot stiffer than MDF board, and when you buy a whole sheet from a supplier you can make up a cut list ( and no cuts that stop half way through a board, they only go end to end, but you can do a lot with straight cuts) and make the top, the shelves and the sides from a single sheet, plus remember the typical kerf of 5mm for the saw, and you get shelves that are same length as the bench, plus the ends and a few centre supports for one price.
A bit of wood glue, some chipboard ( I just use good drywall) screws and some join blocks and you have the shelving done. To stiffen the edge I use aluminium U channel that fits the edge, and this makes it a lot stiffer, plus finishes off the edge as well. Can also be used as a shelf support, and also you can put LED tape into the U and have nice indirect downlighting for the worktop as well. If you want diffused there just get a strip of white thin ( 2mm) acrylic strip and glue it into the U channel just not touching the LED's. A drop of glue here and there to hold it in, and mount the whole strip of aluminium with double sided foam tape.
Made some shelves at work using that method, and they are strong enough that I have no issues walking on top of them when needed.