I have to agree with what everyone else has said. The crowds have really changed over the last 14 year. The low season now is equivalent to mid season a decade ago, and those "low" season days are getting fewer and fewer. It also depends on what's most important to you. You will NOT get low crowds, low refurbs, great weather all at the same time. There are trade offs. I think spring break is worse at WDW than DLR because so many people hate the hot, humid summer weather in Florida, but California is not as bad, so more are willing to go to DLR in the summer, while more hit Florida for spring break. This year the refurbs have been absolutely ridiculous. I felt so sorry for anyone here for spring break because it wasn't low season crowd wise, and a lot of rides were down, making the lines even longer. I have never seen so many refurbs during such a short time in my life. It won't be like that next year for the 60th, and it shouldn't be like this again because hopefully Disney will finish up all the OSHA requirements now.
Lower crowds (no such thing as low crowds now): 1st half September maybe into 2nd half, January/February avoiding all holidays
Low refurbs: summer, Christmas
Weather: November, December, April, May (except for this year--we're having a strange heat wave), even June if we're having a June gloom year.