The rule of thumb is that ORTF is most popular outdoor where there's not as much reverberant sounds, where DIN and DIN(a) are used indoors. DIN and DIN(a) have the 90 degree angle, which vs 120 would tend to minimize the amount of sound that's coming from bounced sources instead of directly from the stage. ORTF is also popular when you know that the venue has great sound...and you'd like to simulate the overall sound in the venue as closely as possible. ORTF is also popular for lip of stage or close soundfield recording.
where did they come from:
ORTF (French) - Office de Radiodiffusion Television Française.
NOS (Dutch) - Nederlandsche Omroep Stichting.
DIN (German) - Deutsches Institut fur Normung
Info from email sent to me from Louie aka NOLAfishwater thanks Louie!!