I recommend Mama Melrose's.
My 90 day window was yesterday, and realizing there are only 3 Fantasmic shows during the week I'll be there, it was the first reservation I made (even though it will be the 6th day of my 8 day stay).
When making my ADR's, I usually start with the first day I arrive and go forward. Not this time. I figured I'd better start with MM F!, and I got it. Lots of people are posting they aren't getting it.
Tip for Booking:
First off, find out which nights Fantasmic is showing during your stay. Don't call and ask. That will just waste time while others are booking it. Know the dates before you call, and pick the
LAST possible one you can attend(farthest from your arrival date). Call right at 7am Eastern (whatever that time translates to wherever you are) when WDW-DINE opens on the day your 90+10 day window starts. Make this reservation first!
The reason you should pick the LAST possible F! date of your stay is because the other shows earlier in the week will be within the 10 day window of people able to book up to 10 days before you! If you pick the last possible date, there are less persons who would be eligible to book this package based on the ADR rules. This will increase your odds dramatically and hopefully you'll get it. Good Luck.