I don't think it's even possible to have a "most coveted pin" anymore. There's literally MILLIONS of them out there now! All different circumstances to their releases, edition sizes, etc. I've never even heard of that "Wet Paint Sign" pin before lol.
You could have a most coveted pin in your own collection, though.
To each their own I suppose. For me, the most coveted pins are the ones I actually want but released prior to me starting the pin buying!
Back in 2001 I think they released the Disneyland Sign series... and man I want them all! That's what I mainly collect. I have a few that WDI released but the older ones actually sold at the park are even harder to come by for some reason.
The 'wait time' signs are awesome but real expensive. I want them but can't afford it.