The point about DUB arrivals on BA into T5 is that there is a clear path to landside, as an arriving passenger, so if HBO normally you can get to the First Wing faster than FCC, it's just above the south exit from the baggage carousels. Now you seem to have a quiet Sunday afternoon and access to the CT scanners in FCC, so it was probably 6 of one, half dozen of the other, but in your shoes, as an Emerald, I would have gone First Wing if there was a clear hour before your next flight's departure time.