I don't know if I have a favourite time as such I guess it's the light. In the winter I shoot less, not because I like the winter light less, but because the shooting times I favour are when I'm at work or getting the kids to school i.e 8-9 am 3-4 pm photographic opportunities are more limited for me at least.
Leaving home in the dark and coming home in the dark restrict my image making to week-ends.
Like Phil said I don't like harsh summer sun, and I'm not a fan of the dull hazy days either, so I guess spring and autumn for the low long shadows and sometimes warmer light.
That said in winter I shoot indoors a little more, but my main constriction is time, I have a few places I'd like to shoot but only under the right light.
Edit I do like the type of light you get later in the day or at dawn and that yellowish autumn light.
Mark