If I had to choose one or the other.... I say it's better having NO expectations.
Having you expectations too high tends to make people get failure complexes or turbo disappointment. Then they are unable to enjoy what they DO get. o__o
...But I can also see where the reverse is true. Some people with zero expectations have zero expectations because they are SO pessimistic and self degrading that they never allow themselves to see possibilities when they SHOULD expect more from things. @_____@
Historical, fantasy, magic, horror, supernatural, survival, vampires, demons, pirates, mutants, ghosts, romance (FxF, MxM, MxF) (Romance should be part of the plot and not the whole plot in itself), etc.
No expectations are better because then I won't get disappointed xD
If I expect to much then it always fails, especially when it comes to my grades x)
So I often don't expect anything or very little and then see what's happening x)