Any nice story with repetitive pattern will do a trick. It �s always nice when children can join in with the reading. Here are just a few that I used and kids really enjoyed them:
Dear Zoo
Walking Through the Jungle, What Do I see?
Knock-Knock, Who is There?
Mommy �s Little Monkey!
You probably know this without me reminding you, but well-known fairy tales always work really well too. My favourite: 3 Billy Goat Gruffs, The Ugly Duckling, Goldilocks and 3 Bears, Gingerbreadman
Also nursery rhymes and counting down rhymes: 5 Little Monkeys, Speckled Frogs, There Were 10 in the Bed, etc.
For the 3-4 year olds I would suggest to use action rhymes and songs.
Hope this was of help
Good luck
Zulia