I think the best spot is WSC Plaza (the center). I have seen it from "the island" in France and didn´t like it because I couldn´t see all the countries and the smoke was extremely thick.
I don´t think the bridge next to Mexico is a good spot, because
a)it´s too crowded
b)the cantina blocks the view of the countries in the left
Norway isn`´t good either because the cantina blocks the view.
If you find a seat at the cantina, could be a good spot, but only if it´s right in the center, not on the sides of it.
Another good viewing point for me is between Canada and MillVill or where it used to be.
Rose And Crown Pub offers a nice view too.
RoE is not that hard to watch from wherever, Illuminations was harder because of the lasers and lights in each country going with the music.