Civil War is tops for me, with Ragnarok and Infinity War very close behind.
Haven't seen SM FFH, and I really enjoyed Homecoming, but I would be surprised if it challenged any of the films above.
TBH I have enjoyed all of phase 3, Captain Marvel and AMATW were entertaining but a bit forgettable. Endgame was great, but a bit long.
Really, phase 3 has been an embarrassment of riches. I think Phase IV may struggle to keep up that level of quality, but be very happy to be wrong.