For a plain one-level menu bar, as you have described, I usually use the list-free option. However, when I have multiple levels, I find it easier to use nested list items.
But it should be considered more deeply than just personal preference. Accessibility plays an important role. What is easier/best for screen readers and voice overs? In either case I will always use
<nav role="navigation">
to ensure accessibility.
Then there is the markup. It is simpler to write nav -> a than nav -> ul -> li -> a.
Lists are hooks for screen readers, e.g. press 'L' for lists
Lists show hierarchy.
Sorry, the above discussion is a bit disjointed, it goes to illustrate my (disjointed) mind on the subject. To wrap it up, I'll stick with what I have done in the past as described in my. first sentence