First to address the wood.
Wood workbench finish. It is less slippery takes all sorts of abuse and best of all can be easily cleaned and resurfaced when needed. Teak would be even better. Varnish will probably offer the longest most durable life. It would hold up without a finish for decades at a minimum.
Recently i had a project that involved making repetitive precise cuts at identical angles and. For a shop workbench i would put on a thinned coat of polyurethane varnish. In my own case i built my current benchtop more than 35 years ago. He didn t say what type of oak he intended to use so i pointed out that white oak would be better than red oak for outdoors because white oak would hold up pretty well without a finish.
If you are really going to do actual work on that workbench top then it won t look pretty very long. If you have installed some big dents or surface distortions over time you can renew the surface by planing it flat provided the surface is thick enough then put the oil finish on once more. We ll guide you to the right finish for your project polyurethane lacquer shellac and more and show you how to get picture perfect repeatable results. Since plywood is a softwood it is much easier for liquid oils and other residue to get into the wood and cause damage.
On saw reference lines speed resetting. Not much will stick to poly and you will certainly have spilled glue oil nondescript goo and other things on the bench over the years. You can finish the other surfaces of your bench however you like with whatever finish you prefer.