Green-crowned Brilliant is another of the mid-elevation hummingbirds fairly common in Costa Rica. I think this is the northern-most of the Brilliants. The male has a fairly distinctive posture with a somewhat almond-shape head and relatively short bill.
The female has a more speckled appearance that could be mistaken for a female Jacobin
The immature male has an orangey malar stripe (and throat)
The Brilliants had a fairly distinctive feeding posture. Sometimes they would hover like most hummingbirds, other times they would somewhat perch with beating wings as they curved their body around the lip of the feeder.