WWDC 2023 is coming on June 5 - Here is everything you need to know about the event!
I actually reformatted my hard drive last night and reinstalled Snow Leopard. I'll keep it installed for a bit and then decide if I want to reinstall Lion, Mountain Lion or Mavericks.I imagine it's those who's hardware is still working fine and won't support anything higher.
I can't imagine going back to SL. But then I was only on SL with my first MBP for a couple of months before Lion dropped.