Now I've looked through the faction listings and overall agree with the categorical placement of most of them. But I think I would have placed them a little differently. I know, there are probably balance issues and fluff issues to consider when trying to pidgeon hole 15 factions into 5 groups of allies.
but I would have liked the traditional forces of order being empire, dwarves and High elves. Empire and high elves became best friends ever since Teclis taught humans magic.
I've always seen woodelves as a neutral faction, and since their fluff is closely tied to Brettonia they seem like a good pairing. Tomb kings is also neutral too I believe, or at least not out to kill everyone..just nagash. (not too sure about that though)
Like I said before, allying the factions isn't easy, so I am not too fussed if they left as is for the grand campaign.
Lastly, I'd like to try a giant faction on faction battle (2 vs 2, or even 3 vs 3) e.g The chaotic vs The Ancients.
There might be some issues there with deployment and power dice but we can cross that bridge when we get to it. Who wants to play some Fantasy Battle?