Pictured is a 2-2/4 inch thick edge grain walnut kitchen island top with torino edge profile and penetrating oil sealer.
Sealing butcher block countertops needs to start with asking "what are you going to do on the top".
Some wood kitchen countertops are used as food prep areas where actual chopping will be done. For the most part people refer to this type of wood surface as butcher block. They are perfect for this use and proven over hundreds of years. The best sealers for these tops are mineral oil or butcher block wax, which is just mineral oil, food grade mineral spirits and beeswax. These are not really sealers but more of a way to keep the wood healthy and reduce the chance of cracking. It will stain and water will be able to penetrate so they are not good choice for kitchen countertops with sinks.
The second type of wood countertop is just that a countertop made from wood. It's designed for heavy use but not for cutting on. The sealers of choice here are the marine varnish or the Rubio Monocoat oil. They both perform and look very similar with the only real difference being the sheen. The marine varnish is a top coat with a sheen similar in look to a furniture piece. The Monocoat has no sheen above the sheen of the raw wood making it look much more like a butcher block top with the added protection of the marine varnish. Both are great around water and both can be used in a commercial or residential environment.
(Our personal favorite.) It starts out with zero sheen much like a typical butcher block top but sheen can be increased using Monocoat Universal Maintenance Oil. Perks include easy sanding and spot repairs, excellent water resistance and superior stain resistance.
If you're looking for a furniture style countertop this is the sealer for you. A very durable finish with sheens from satin to high gloss.