It's mostly 777's in the winter season and a mix of 777's/747's in the summer based on my experience. So what your seeing now (summer timetable) is likely to be completely different in the winter. It also changes quite often and close to the flight, back when myflights was a thing, it wasn't uncommon for a 777 to change to a 747 a week or two before the flight, however I have never had a 747 change to a 777.
Pick the busiest flight and hope for the best.