The answer to the question depends really on whether you expect to enjoy or endure your flight.

If the flight is purely to get from A to B in a fit state, then temperature and noise would be the 2 factors most likely to spoil it for me. The first is worse because there's not a lot you can do to mitigate it personally.

If it were a daytime flight, the food and IFE gain more significance. Yes I could watch films on my iPad, but that means thinking about it before hand and downloading them.

I have slightly higher expectations of the enjoyment factor when I'm travelling for leisure, rather than business.

You know the hard product before you buy it so that isn't usually a factor (unless its broken in some way).