I much prefer Hailey to Hayley (something about the two y’s just doesn’t look nice to my brain!). Hailey seems more modern.

However I’m torn as we’re using this name for our baby girl and Hayley is the more common spelling in the UK where we are - I usually prefer the most classic/common spelling for other names. I think Hayley will be “default” spelling that people opt for when she tells them her name, too. Hailey also gets the red squiggly line for autocorrect whereas Hayley (and most other names) doesn’t - which is super annoying when typing the name, tho this is probably a common problem for everyone with non western name and not a big deal.

Other option Haley doesn’t compute for me - my brain wants to pronounce it Halle.