Most of my Vita time was spent with Persona 4, Stardew Valley, and Lumines. It's embarrassing to realize that all three games eventually got ported to Switch. The Vita version of SV is frustrating now, because it's stuck at 1.2, while version 1.6 is available on other consoles, computers, and mobile devices.
I enjoyed Geometry Wars 3 and Everyday Shooter on Vita. They're quite similar: no story, abstract graphics, and arcade style gameplay. Neither one ended up on Switch, though the console offers similar games.
My favorite PSN purchase of a PSP game: Lemmings. There was a Vita edition with touch controls. I tried it, but didn't like it as much.
Finally, my favorite PS1 purchase was Harvest Moon: Back to Nature. I'd been enjoying the game since 2000. In 2013, I could admit its flaws. However, I kept replaying it as recently as 2020.