My first choice would be Feb 2- 8 and my second would be Jan 12-18.
Our upcoming trip will be our third time during the last week of Jan/first week of February.
The crowds are at their lowest! The only downfall is that the parks close very early during those times. But I think the lack of having to wait in any long lines more than make up for that!
You do have to pack a little bit of everything though, sweatshirts, long pants, as well as shorts and tee shirts. It can go from the low 80's for a high during the day, to the low 60's during the day, so it's best to pack it all and be prepared!