I just learned about pete the cat this year too! DD1 started jk in September and also went bonkers for the pete the cat books she saw in the book order!
We started getting Robert Munsch books from the library around 3yo (some audiobooks too where he reads the stories) and the girls both love them. If we see a Robery Munsch book in the book order with the audio cd we usually get it, because its much more fun when they hear him tell the stories! DD2 even loves the books, I caught her trying to sing the mortimer song while flipping through the book one day, cutest thing ever!
Julia Donaldson is big in this house too, along with Eric Carle (hungry caterpillar, etc.) We got Steam Train, Dream Train from the library (same author as construction site) and dd1 loved it, I'm sure your ds would too
We often get Franklin books from the library, dd1 has liked those for a long time now.