We needed an 'other' option.
I mostly prefer Lois with long hair - I never thought that they got a short-haired style that really suited her as much as that delightful bob of the first and second seasons.
But there are exceptions to that. There are a few episodes or scenes where I thought she looked lovely with short hair. None of them are coming to mind right now, but I remember there were some.
In too many others though I thought the styles made her look haggard or even ill. Tempus Anyone? is a good example. Love the episode, but I think her hairstyle there is dreadful, far too harsh for her face.
So, my answer would be mostly long-haired, but not entirely. Just to be contrary.
LabRat