I still think 2nd person is the guy you're shooting at. Lol.
I never did say how I use 1st and 3rd.
General movement: 3rd person
Building: 1st for ghost placement, 3rd for everything else. 1st in close spaces or detailed areas.
DM-ing: 1st person for accuracy, zoom, etc. and 3rd for running around and such. Also for shooting at someone with a splash damage weapon like a rocket launcher.
Macroing: F8. :3