This is not a case in which one choice will be perfect for everyone. We all have different preferences when it comes to appearance, so the key is to go with whatever pleases you. Overall, smooth and glossy finishes are more popular for tables. Most tasks for which a table is used can be done better with a perfectly smooth surface.
As a first step, decide if you want to alter the natural look of the wood. If so, you will want to use a stain of some sort, and you might also choose an oil-based finish to darken the wood while giving it a rich shine. If not, your wood sealer and/or polyurethane top-coat should bring out the grain very nicely without changing the natural appearance in any major way.
If we had to pick one option as the best, I would recommend an oil-based polyurethane product. This will provide the desired level of smoothness while also giving the most long-lasting finish. A table will normally see a lot of hard use, and many different things might be spilled on its surface. Thus, you need to go with the heavy-duty stuff here.
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