Back when I flew regularly the MD-80 and derivatives where my favorite planes to fly because of 5 across rows with wider seats than the 6 abreast 737 which is like flying in a cattle car.  My least favorite for long haul trips was the 777.  Twelve hours where the seat armrest would go up only part way was too much.  It made it very difficult to take advantage of adjacent vacant seats or just cuddle with my wife.