Alfar will be a very united nation : every other race being ennemy, it helps creating a sense of community. Problem : it may be the home of a lot of RPK which will ba a problem diplomaticly-wise.
Human / Dwarf / Mirdain will be the exact opposite : lot of new players, the real zerg playing how they can and throwing the responsability of all their failures to whoever they can.
Ork / Mahirim may be a good compromise. They may lure a lot of newbie (orks, werewolves are the shit) but they won't have the carebears in. A lot of RPK surely, less community sense than the Alfars but less diplomacy problems.

[Linked Image from w3.the-kgb.com][Linked Image from w3.the-kgb.com]