Best HH audiobook collection/anthologies?

I have, at long last, begun my journey back in time into The Horus Heresy. (My boy did nothing wrong and was lead astray, fuck Erebus). I have already bought the entire Siege of Terra series and a fair portion (read 25-35%) of the HH books thus far. Looking at a lot of the short stories and novellas, there seem to be multiple collections that each contain similar books, some seem to be very close in what they contain. Is there a consensus or anyone who is most familiar with which collections are the best bang for the buck as far as collecting the short stories?