I'd skip the ternary and go with

foo = Optional.ofNullable(bar)
        .map(Bar::baz)
        .orElse(null);

But if I didn't, I'd use the first form.

I actually prefer

Optional.of(bar)
    .map(Bar::baz)
    .orElse(null)

You can crucify me but there is no way to miss the point in a quick glance here and I doubt that with JVM optimizations there is any meaningful performance impact, exceptionally in business code.

The second, or early return/continue/break.

But don't forget the third option:

foo = null
if (bar != null)
    foo = bar.baz();

This is much more readable if nontrivial; the only downside is that this inhibits the practice of ubiquitous final.

Actually, doesn't Java allow lazy final if you don't initialize (that would require explicit else)? I speak too many languages ...