I understand the GTVA's motivations, especially considering their whole reason for still existing is built around the fear of some (very real) cosmic bogeymen, but I feel they jumped the gun with this war, no matter how much the situation was FUBAR'd following the 14th's little inter-universal jaunt.
I suppose I support the UEF more simply because it's them having their homes invaded, and you see this from their perspective during the campaign. As far as looking at the big picture behind both Governments... I dunno. The GTVA is easy to understand, but the UEF, being based around what strikes me as Scientific Mysticism with a bit of Gandhi thrown in for the hell of it , yet also having an incredible industrial base and enormous productivity, seems like it could be a massively dangerous force if there was ever a shift towards more war-oriented policies. It's a bit creepy when I think about it.