VLC for those ancient videos haven't bothered to transcode yet.
Firefox/Chrome because Youtube won't support h.265
For in ecosystem stuff
iWork suite if you don't want to get the Office suite
Xcode if you want to compile anything serious (and not just for iOS stuff)
My old work was unix based so I wanted something unix based at home. Ran Linux for a long time but made the switch to Mac when they went x86 for better peripheral support.