I'll be honest with you- most alliances are extremely similar. It depends on what you want- do you want to be in a large alliance that likes to netgain? LaF is probably your best choice. Do you prefer war? SoL is there for you. Do you want to be in a big alliance, but not one of the huge ones? SoF wars well, Evolution nets well, MD, Paradigm, and LCN do a bit of both. Do you want to be in a smaller alliance where you won't be one of 60 or more people in the crowd? There's plenty of those.
It depends on what you like to do- shoot for a high score, or kill other countries. What I suggest is checking out the ingame stats, figure out what size alliance you want to be in, and what you want to do. Once you decide, you can find most alliances' homepages here.
http://wiki.earthempires.com/...Alliances#Alliance_Server
I'm personally with Neo Federation, we came back this set, and we prefer netgaining- we're a smaller, more close-knit alliance.
http://neofed.fsenthusiast.net/Home/index.html
I hope you enjoy wherever you end up- welcome to the server!