Our favorite busy time is the week after Christmas. You can still see all of the decorations and special events. It is very crowded, but if you get into the parks early and use FP efficiently, you can get everything you want to get done.
We have gone several times over Spring Break and have been absolutely miserable. It’s hotter in the spring, and the spring breakers are everywhere. Check to make sure that your spring break doesn’t align with college spring break before you book.
I actually don’t think the third week of June is that busy. It is hot, though. Still, if you get into the parks early and use FP efficiently, you can get everything done. We like to get into MK at rope drop of EMH. We can then get all of the “E-ticket” attractions done by noon. I would guess that of the three busy times you’ve listed, the third week of June will be the least crowded (not to mention least expensive).