It is generally considered to be the highest academic qualification that you can study for. However a PhD is a research degree - a training in research methods. If your chosen career has no need for research skills, then another qualification or some work experience will be much more relevant.
There are also other degrees and society fellowships which are often conferred on very senior academics for important contributions to their field. They are higher qualifications than a PhD, but you can't exactly study for one or usually even apply. They're kind of like a lifetime achievement award at the Oscars, but for clever people.