I'm a fan of absurdly colorful art styles, personally. Majora's Mask, Chrono Cross, Grow Home, Okami (to a certain extent), and Jade Cocoon come to mind. Broken Age, for all its problems, is a pretty stunning game in its own unique way, too.
But Chrono Trigger is at the very top of the pile for me. It's colorful, but knows when to use that to create atmosphere and when to stick to something more muted. The sprite work is unparalleled to this day, and there's enough detail to separate and differentiate parts of the game so well that I can remember area layouts despite not having played it for years. And that 600 AD fog! Ah, memories. In fact, that might be all nostalgia. It still captured my imagination way back, though.
Oh oh oh, and Seiken Densetsu 3 is gorgeous for a lot of the same reasons. I'd always use Angela as the main character to start in the area with trees that have
Christmas lights on them. So wildly impractical and pretty. Little touches like that really add up.