I rarely use crowd calendars as, IMO, it's not something to completely go with. However when I have looked at them, I highly prefer easywdw over the rest.
But for December, it's still too far out. If anything, look at 2015 crowd calendar for December to try to get a feel. Also take into account all the party nights for MK.
But as of right now, if you're planning on making ADR's soon just keep checking hours as it gets closer. Park hours for December aren't finalized, EMH's will be changed around, etc. Pretty much the only guarantee to go off is planning around the party nights. If you're trying to book so you can get early adr's and try to beat rope drop crowds..it'll be hard to do with booking anything more than about 2 months out
Or just wait a few months and make your reservations when things are more set in stone. I know people like to book 6 months in advance, but from my experience in booking any adr's, I've found A LOT of options available just a few weeks out.