Simplest way would be to set the Customizer > Layout > Container > Content Width to match that of the image in the Header Element which is 1024px.
Also take into account the container padding so setting the width to 1104px wide should do the trick.
Envira Gallery and Foo Gallery are pretty popular with our users.
We haven’t had any reported issues with Essential Grid.
One we try to avoid is NextGen – let’s say their code likes to leak outside of its own scope.