Fundamentally both are correct its really a matter of what it is you are trying to understand.
Basically if we look at a segment using HIT the I like to think you are more interested in singularly just that page or groups of HIT based pages your segment defines.
If you desire to understand users journeys involving a key page and then any other subsequent ages then VISITS is the way to go.
Hope it answers your question. If not then I need more context into specifics of what you are trying to understand.
regards