well, in terms of public income ARD is probably the biggest but just cause of their multiple children …
https://de.statista.com/statistik/daten/studie/196121/umfrage/gez-einnahmen-nach-rundfunkanstalt/
But it is very close to the other German Public Broadcaster #ZDF …
In terms of reach the ZDF leads with 14,7 %. The ARD reached 12,1 % …
But it does not matter cause @ZDF is in Fedi too and even for longer :)
Please do also note https://www.publicmediaalliance.org/public-broadcasters-create-public-spaces-incubator/