The spelling I’d probably use: Katelyn. I like the elegance and straightforwardness of it, and I prefer the look of the K over Catelyn, though I could get behind both spellings.
I also like Caitlin for it’s more authentic origins, though in the Irish language I don’t think it’s pronounced quite the same.
If I were gonna go off the beaten path, something about Katelind/Catelind appeals to me. I love a Lind name (always had a soft spot for Lindsay), but I would definitely pronounce it with a strong d sound at the end and I don’t think that’s quite the same name at that point.
My least favourite spellings would have to be Cayetlan or Keightlynne. There’s just a bit too much going on and I don’t think the complexity adds much. I think for me the appeal of Katelyn is the simple, approachable sound and the complicated spellings chip away at that friendliness.
Combos: Maybe Georgia Katelyn, Caitlin Madelief, or Suvi Katelyn “Sukie”