A quality cabinet grade plywood should not warp. but if that is you fear, here is a solution.
You will need a perfectly flat surface to work on. Make the top of 2 layers of 3/4 " ply.
Glue and screw them together. Apply glue to one surface lay the other piece on top of it. Clamp them down flat with the table and screw them together. That flat surface should never warp again.
I have always edge banded my router tables and assembly tables and then laminated the tops with Formica or Wilsonart brand of plastic laminate. The table should last a lifetime.
I have never used plastic laminate or a backing sheet on the bottom. If you go with MDF, use the same procedure except a bottom layer of backing sheet of plastic laminate will be required.
Tony B Retired woodworker, among other things.
"Strive for excellence and settle for completion" Tony B