Recently been picking my flights based on aircraft. The 777’s seem to be less shabby and seats are more comfortable for me. It may be that the 777’s always have the adjustable headrest which for a tall person is a must especially if you are on a red eye.
Other thing and it may be coincidence but if u think back every long flight I have taken in a airbus 321 has ended in a cold for a couple of weeks.
For those reasons alone I am going to look at aircraft type when I book a flight.
YMMV. But that’s the travelgrumps opinion.