Best is subjective. I don't think either of the other two player nations have a dreadnought with a better battery. In that circumstance, the Lorcan-class would be on par with the other nations.

Whether or not you need bigger guns is also subjective. Nations usually up gunned their ships in response to a rival upgrading their own guns or armor. But in game terms, a 2 rating for Battery would be larger guns than a 0 rating.