Going for a quick three day trip in July with my son and two nieces ages 20, 16 and 13. I got us Park Hoppers so that we can visit all four parks. I have scheduled a HEA Desert Party on a night that there is evening EMH in Magic Kingdom. I also plan to do EMM in Magic Kingdom on our first day there so that we can knock out Fantasy Land. That afternoon we will probably rest for a while and then hop over to Epcot for evening EMH.
Taking the Magic Kingdom EMM and EMH (later in the trip) plans into consideration, would you make fast passes in Magic Kingdom for the morning to follow EMM or would you just do EMM and try to do some of the mountains, Haunted Mansion, Pirates, etc after opening through standby and then make our fast passes for later in the day at Epcot? I am not sure how many more times we will get to do Epcot during the trip.
What is the projected crowd level that day? I feel like i would do epcot since riding TT, soarin, or FEA will be tough in the afternoon, and you won’t want to standby all three. But you get more out of your fps at MK because there are no tiers and just generally more rides. That said, my gut is to go with fp at epcot.
Crowd levels are a 6 at MK and a 7 at Epcot. My gut is the same as yours with the same thoughts about really wanting to use them at MK to get more bang for my buck but we will definitely want to do some of the big rides at Epcot!
Thanks for your thoughts!! First world problems! 
I’d book EP because of this: If you do MK FP the earliest you could book a 4th for hopping to EP would be after 12pm if you had 9am opening. Depending on crowd level the Tier 1 FPs may already be taken for the day.
It depends on which rides you want at Epcot - the rides at Epcot are never must do for us on our trips and we do them if we get the chance, the real draw of Epcot is WS. So I would do FPPs at MK and the try for a FPP at Epcot when using your last one at MK. We only then do single rider for TT and play the rest by ear. Of course, if you have must do rides at Epcot then do the FPPs for them.
I think it depends on what your priorities are in Epcot and how long you’ll stay there that evening. FW rides’ lines all tend to get pretty low later in the day and I’ve been told (though never attempted) that Soarin’ is a relatively easy 4th FP to secure. You could also utilize the SR line at TT as a potential for skirting around that standby line. Then you could just plan to do SB for Frozen. The queue is inside and in glorious AC which will be a welcome relief in July!