That all depends on your motivation for measuring and your health history/background.

pulse wave velocity is, in my eyes, one of the most important biomarkers for vascular health and, by extension, for longevity and healthspan. I have discussed this subject in my post on bioage (https://medium.com/illumination-curated/embrace-your-bioage-abandon-your-calendar-age-say-scientists-7430eff3830f)

Principally, the measuring is just the first step, as popularized by the Quantified-Self movement. The real benefit comes from reading the data in the context of a methodical N-of-1 self-experiment.

Any biomarker of interest that is also accessible for daily monitoring is fair game for this approach to lay-person-capable DIY lifestyle medicine.