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.
Bedridden homemaker needs good drugs: "Clearly, she's a hypochondriac and addicted to antibiotics. No, bitch."
Same woman, different scenario:
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."
Still alive nearly 15 years later.
The "most valuable" one for me would have been the (Cisco) CCNP.
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.
Microsoft certified professional (MCP) in Visual Basic 6 in 1999, no longer offered. Made a lot of money on that one.
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.