Hello, I am aligned to the Alliance and have been since they launched PowerPlay (whenever that was). My main reason for doing so was according to Elite Lore, the Alliance helped the Thargoids with a cure to the virus that was released, to kill them.
When (or if) there is some Thargoid/alien invasion or war, I think the Alliance will be the side to be on. I might be totally wrong about all of this and got my facts wrong but who knows.
Anyway, although I've not actually done much Alliance stuff of late, only ever managing to get up to Rank 3, if my memory serves me well. It was quite a hard slog to be honest and keeping it up at that rank was also hard work.