I currently have 18, 27, 35 and an old manual 50. Not planned, the 18 and 27 came with the camera.
I'm addicted to the 27, oddly! I love how tiny it is and have just got used to the field of view. The 18 I just never use.
Totally unable to bond with the 35, which I expected to adore. Field of view is either too narrow or too wide, and I love wide apertures for narrow DOF rather than low light performance but at 35mm that hardly happens. Should have saved a few more pennies and got the 56, which I can see myself trading to soon anyway.
Then I just came back from a road trip where zooming with my feet just wasn't an option on so many occasions where I could see a shot. I missed my old canon 100mm like crazy. So could see myself ending up with 27, 56, 90.