Pompeii offers a complete view of how life used to be in an ancient commercial town.
Herculaneum instead was more residential - more relaxed - and one still gets that feeling nowadays when wondering along its streets.
Herculaneum is more compact, smaller - less walking involved.
The visit will include beautiful frescoes, stunning mosaics, the skeletons, shops and a bakery, the public baths, the small - but great - Museum of the site and plenty stories and mythology.

So, it’s not really a matter of which is best but perhaps it’s what you think would suit you best!
We strongly believe that a visitor should see both of them as different dynamics of the eruption preserved the towns in two distinct peculiar ways.