Choosing the best type of wood for your workbench top depends on both your budget and on the type of work you plan to do not to mention your own aesthetic preference.
Best wood stain for workbench. They are as durable and easy to use as acrylics and highlight wood grain as well as alkyds. Acrylic stains are what people think of when they refer to water based products. They are more durable and provide greater protection than alkyd stains but sacrifice the beauty of wood grain. A good coat of wax is another option.
The poly will let you clean up pretty well. Minwax wood finish penetrating stain at amazon great for restoring the natural beauty of wooden surfaces like older tables and cabinets that have been worn by use and age. You can t caulk a bench like you do the framing around windows. For a shop workbench i would put on a thinned coat of polyurethane varnish.
It is less slippery takes all sorts of abuse and best of all can be easily cleaned and resurfaced when needed. Each type of wood has its own peculiarities which will be explored below in order to allow you to make the most informed decision possible. A workbench as its name implies is to work on and frankly the best surface to work on is raw wood. If he insists on applying a finish maybe for looks or to make the surface smoother a boat varnish from a marina would be best because it would hold up better against the sun s uv light.
Acrylic oil stains represent the best of both worlds. General finishes jq gel stain at amazon boasts overwhelmingly even coverage that ensures a natural appearance without penetrating too deeply best budget.