First Class has been eclipsed by Business Class.
When I first travelled Upper Class on VS (Oct 1986) it was certainly very comfy but not lie-flat. I think it was them (and probably others) that started the move to make C a lot better. Subsequently, various financial crashes, 9/11, Covid, NetJets etc. have meant that F is now for wealthy leisure more than the CEO types. Further, many of those travelling on business have been told not to have 'First Class' show up in their expenses.
Accordingly, C became better than many F. I think that one carrier changed it to 'Business First' to get round it?
In the 1990s, these changes meant that PE replaced some who went C as the prices increased and for leisure who could afford a bit more. As C improved, so PE has also crept up the scale. F is out on a limb.
I have never travlled F, C and PE suit me/us fine. If I had the cash to splash, I'd try some of the more exotic options. When comparing carriers - C is now the standard.
I lie down with a glass of bubbly. If you wish to correct me, do knock on the sliding panel first ...