Species with vertical pupils are more likely to be ambush predators that are active both day and night.
Vertical pupils are better for judging distance by reducing binocular disparity (the effect where if you focus on an object and close one eye, the object appears in slightly different places in each eye individually) and blur (where objects at different distances are out of focus). Slit pupils also allow much greater control of light with dilation and contraction at a 135 fold difference in some animals
(compared to 10 fold in humans), which protects their sensitive eyes when they move around during the day.

Animals with horizontally elongated pupils (like goats) are likely to be herbivorous prey species with eyes on the sides of their heads.
Horizontal pupils expand the field of view, and also means the pupils are parallel to the ground so they can see better while grazing or browsing and limits intense light directly from the sun. They can't see as clear an image, but they don't need a crisp image of an approaching predator, they mostly just respond to movement.

Circular pupils are linked to active foragers, or animals that chase down their prey. They're also found in taller animals.
They see well in low light
(i.e. dusk and dawn) and daylight conditions, but not so much overnight. We typically see better color and details, which is useful for identifying fruits, berries, etc when foraging. We have a wider field of vision than slit pupils, though not as wide as horizontal since we're still potentially prey animals and can detect movement at a distance.

And there's a few other weird shapes which are more specially adapted to their specific niche -
like W pupils in cuttlefish (in bright conditions) which have two fovea in each eye so they can have a clear view in the frontal and caudal periphery of the visual field, as well as greater ability to adapt to varying light conditions,
and pinholes in some lizards which are great for detecting perfect striking distance.


https://www.reddit.com/r/askscience/comments/fr7oo0/what_is_the_advantage_of_iris_vs_slit_eyes/flubhh5/