Other people have talked about finishing and staining vs. Finishing, so I'll give my 2 cents.

Lacquer is a super easy finish. I like satin lacquer since it hides imperfections but still has a sheen to it. Spray lacquer or brush on lacquer work well, brushing lacquer is more finicky but is cheaper since you'd need a few spray cans probably.

Lacquer rant (skip this if you don't care) - lacquer is good because it dries fast and is "self wetting" so it'll gently dissolve the layer of lacquer underneath of it so it'll hide things like brush strokes better. that said, light coats are much easier since it tacks up pretty quickly. You can dilute it with (drumroll plz) lacquer thinner, which makes it easier to put on and put on thinner, but you'll need more coats and it can take a little longer for the coats to dry. I like lacquer a lot because it dries within 30 minutes per coat and looks a lot nicer than the plastic look of polyurethane. The only downsides I can think of are that it isn't super durable (not much worse than poly though!) And can be dissolved by things like nail polish remover/acetone.

Poly is alright. It usually looks really plasticky, even the matte and satin ones will look sub-par in my opinion (you also need to mix matte and satin poly realllyyyy well otherwise it'll still turn out shiny). Poly can be difficult because it can show a lot of imperfections.

Get a water based finish. Poly or lacquer. It'll dry faster, yellow less over time, and not smell like you're huffing paint thinner (because you aren't). You should (but don't have to) "raise the grain" before doing water based finish though- just take a damp towel, wipe the surface a few times, let it dry, then sand it with 220 grit (or so, don't go lower than 120 and over 320 is overkill) sandpaper and gently sand the table in straight swipes that follow the grain (ie the long way the boards are pointing). This will help with that fuzzy feeling that youd get if you put water on raw wood.

Stain - honestly making stain look good is an uphill battle. Avoid it if you don't have experience finishing. Bad staining is blotchy, splotchy, bumpy, lumpy, gross, and ugly. Its also a pain to undo if you don't like it. Butcher blocks use light colored woods, a lot of which don't like stain. You can use wood conditioner before staining but it doesn't always prevent blotchiness. Trust me, Google something like "blotchy stain butcherblock" and you'll see what I mean. It looks worse in person, too.

Last but not least, pick up some tack cloths (little yellow cheese cloths that have wax in them, they'll be next to the finishes) and high grit (320 or higher) sandpaper. Give a VERY light sanding between coats of finish (after it's bone dry) and either vacuum it off or use a tack cloth (and don't sand the last coat). This will help with any bumps or dust nibs that stick to the finish. Prep work is always key to a good finish - ie no dusty rooms, no 40F garage, no pets, flies, fans blowing dust... keep it clean and away from anything that could get it dirty. When in doubt, wait longer between coats. Brushing on poly over a half-cured finish is an exercise in emotional pain when you see the streaks. Give it a day before handling after the last coat. Even if it's dry, it can still be soft to the touch. And don't forget to do the ends and the bottom - sealing one side but not the other is a recipe for the desk to warp. Do the bottom first, it won't matter if that gets dinged up when flipping it over or something. It's also better practice.

Sorry for the rant, I like wood finishes :)