Of course, not all humans are part of the Imperium (no matter how much the High Lords of Terra would like it to be so) there are Rogue Traders, and even Tau auxillaries. And of course, there exist many minor human realms not in the rule of the Imperium. Of course, the lifespans of such realms are short because the Imperium will not tolerate empires besides theirs.
Wolves are just boring. Vikings in space, with next to no references. Well, being plain and boring is the whole point of Space Marines. No offence to Marine players, just explaining my view. Eldar, on the other hand, have really many mystics going around every aspect of their lives. It's fascinating. Also, any Left-Winger should play Eldar because they've created Communistic utopia.
Humans have a similar purpose to the Eldar as do all races. Survive. The Galaxy is filled with countless dangers so almost all of them have become so xenophobic anything with too much difference is "eliminated" before they can do anything that might damage them. Humans have a lot in common with the Eldar even though the Eldar and Humans really don't like to admit it. Eldar just have a more direct purpose while Humans are more free. Humans can dedicate themselves to something while they could also live care free and just go without direction. Main reason why Humans are awesome in the 40K universe. I will play and keep playing Eldar just because they are Elves... In Space! Elvish lore in all games about Elves is always great, Elves always have a more mysterious feel to them and also Elves usually are the masters of Magic and Ranged combat in games. Usually... The fact they have hot space chicks in space has nothing to do with it at all.... I think that Eldar will cope with the lowest Pop by letting the younger races fight and we swoop in and kill the stragglers as we take the victory. =D
My reasoning for the Eldar is shared by those whom have posted already. Rich and engrossing lore, interesting aesthetics, and an underdog with serious odds against them. I also really love the whole fall of an entire civilization deal. They became too enamored with hedonism and debauchery that they birthed a new chaotic god! In so doing wiping out 90% of their race, enabling the humans to begin their cancerous galactic take over, and signing their own inevitable genocidal doom. How's that for incentive to become isolationist and bitter? Also the idea of their seer councils and Farseers steering the course of history in their favor with battle tactics and as mention the manipulation of "lesser" races for their own gain. Wonderful, especially when they maneuver an entire human planet in front of an advancing Tyranid Hive Fleet in order to divert their advance on the Craftworld. Devious and cold. I love it.
I like all the factions, but Space Marines and Orks are too bulky for my taste, so Eldar it is. But if World Eaters, Night Lords, or Raven Guard get added I may jump ship.
