RHCSA has probably been the most useful in terms of applied knowledge, while a few various AWS certs (associates, sysops) have been valuable in terms of being a consultant at an AWS Partner. I've found being able to demonstrate knowledge through experience by completing personal and professional projects to be more valuable long term though.
Certificate in GIS, though not really for the reasons you list. I value the knowledge it gave me. I value more the drugs it got me.<p>Bedridden homemaker needs good drugs: "Clearly, she's a hypochondriac and addicted to antibiotics. No, bitch."<p>Same woman, different scenario:<p>Newly diagnosed with CF, borrows $19k to go to a summer tech boot camp: "Sure, honey, what drugs do you usually prefer? Here, let me tack on a few more for good measure."<p>Still alive nearly 15 years later.
The "most valuable" one for me would have been the (Cisco) CCNP.<p>At a previous employer, though, we would get a raise for earning various certifications so I took a bunch of them that I wouldn't normally have taken. Most were worth at least a $1000 (USD) raise (added to my salary) and some (i.e. CCNP) were worth much more.