It all depends on the person, personally I would prefer the spacex method as I don't have to put on a brave face for someone who is firing me. I also don't have to walk through the office knowing everyone is feeling sorry for me. The warning also gives me a day or so to brace myself in private at my home for the email so I am not caught completely off guard.

Also they fired 10% so there was a 9/10 chance they would be keeping there jobs.

No matter the method its done, everyone emerges from a layoff knowing that they are just a line item on a spreadsheet. Its unfortunate but true.