I think you’re referring to “Observation of the Day”? If so, I’m normally the person who chooses and posts them, unless I’m away. If so, another staff member chooses it.
I generally look at “popular” (meaning faved) recently-added observations and choose one every day. I try to keep it diverse geographically, taxonomically, and demographically if possible, and I basically consider it a way to share what’s possible on iNat. So I try to make sure that the photos aren’t all taken with expensive equipment, for example. The number of faves don’t usually factor into my decision. People can always message me on iNat (not here) if they come across a cool observation. In general I prefer to be sent observations made by someone other than the person messaging me, because it shows that the observation caught their eye.
As my profile says, please don’t @ mention me in a comment on the observation for this purpose.
Awesome! Keep in mind that iNat gets tens of millions of observations a year and only 365/366 get chosen as Observation of the Day. It’s impossible to share all of the incredible stuff people are posting and it’s a bit of the luck of the draw as to which ones get chosen. Just because an observation isn’t chosen doesn’t mean it isn’t cool, interesting, or important.