We really like Harmonious now. We loved Illuminations and while a non IP show seems better for EPCOT, loosing HEA at MK was just awful. This at least fills some of the void for us anyway. Plus it is visually stunning and very good fireworks. It's quite a bit longer as well.
As for where to be, by far the best is dead center out from SE. It's seemed closer to the fireworks and obv the screens are set with the spot in mind. That said, many spots are plenty sufficient around the lagoon. And as we see it over the years, pretty sure we will be walking around with a drink while it goes off-still loving the songs and taller fireworks.
Height (or waiting in a front spot) obv matters if you want to see the projections, we had a taller group and lately have found quite a bit of open spots right out dead center, and it rises a bit anyway so it's not a bad spot even as showtime approached.
Wind. The smoke in your face does take away some clarity, maybe base that as your spot choice. Yet weirdly one night we were out dead center with the wind in our face (no bugs in our teeth), and some of the laser/projection effects where enhanced. But other visuals did get a bit fuzzy.
Other spots we like are as others have said. Just right of Japan, or out from Italy. Then the CA and Norway spots are pretty good as well.