I was really pleasantly surprised by Dr Seuss. Not a series I grew up with at all, had heard of him of course but had no emotional connection, if you see what I mean. The rhymes are a joy to read, they scan beautifully, which is something they have in common with Julia Donaldson, they are a pleasure to read. For slightly older kids The Lorax is a really thought-provoking story. I also like Yertle the Turtle.
I second the recommendations for the Oi! Books and You’re Called What?
Tiger who came to Tea is a gold-plated classic, so much so that I bought an extra copy and framed several of the pages for DS’ bedroom wall.
Hairy Maclary I love, though some are better than others, the one where he ends up in the garden centre after getting locked in the delivery van is my favourite after the original, also Slinki Malinki.
An unexpected favourite that someone gave me was Ten Little Fingers and Ten Little Toes by Mem Fox. It’s for really little ones though.
The original Where’s Spot? is great with its 1970s drawings, the others are a bit rubbish though.
I loved Mr Men as a kid but as an adult I kind of feel that a lot of them are actually portraits of people with metal illnesses!
You Can’t put an Elephant on a Bus! and its sequels are great.