I would choose Lord Gregory.,not only because I prefer it but KNOCK EM IN THE etc,is readily available in printed form,and in my experience is less likely to have intersting varitions melodically,and lyric wise.
also, as a collector,does the commercial aspect come into play?is the collector more likely to sell[or get published] interesting versions of lord gregory ,than of the former.this may not be of importance to the part time collector,but a full time collector,who has to pay his bills,from the proceeds of his collecting,may have to take this into consideration.
I suppose Jim,you have to be very careful how you phrase your questions,and also try not to indicate with body language,your own preferences,so that you get an honest answer,it must require alot of skill.