I quite like the Gruffalo, but my DCs are not that keen on it. Although I can't find my our copy of the Gruffalo so haven't read it to them in a while.
Our favs are Stickman - love the rhyming in it. Fetch it and drop it and fetch it again, drop it and fetch it and drop it again..!! Genius!!!
Tabby McTat..a cat-to-cat chat...love it!
My personal favourite is Zog, for the feminist angle 
YY to Room on the Broom too. And Cavebaby is great, DS loves that one.
I absolutely adore Monkey Puzzle, but the DCs get a bit bored halfway into the book because it is a lot of reading and becomes quite repetitive, so I tend to skip a few pages. But I love it for the storyline though.
Love the What the Ladybird heard too. I don't think the DCs get the story tbh, it is quite complicated for an under 5 I think. My DS who is 4 can just about understand the plot.
I hate the Hungry Catterpillar too and the DCs don't like it either. We do like the Tiger that Came to Tea however, DS is really engaged by the storyline. I took him to see the stage show a few months ago and it was pretty good, even I enjoyed it.