I like role playing, but that doesn't greatly influence my choice of wargaming. Once I got the concept of Warmahordes being a story in progress, I had no problem with only having named characters (though I would like to see them make special scenarios involving the battles the characters fight ala Forgeworld). I also don't have that problem with FoW. I do like that in GW games (and to a lesser extent warmachine) you can make the army your own. In that regards I think GW stands head and shoulders above the rest.
Dan also makes a good point about the changes being made to make you get new models or new armies. I'm use to that, though it has never hit the guard anywhere near as much as the change from infantry hordes to armored cans like the 5th codex does. My regrets with Grey Knights is that it brought back a feel of the 2nd Ed. Chaos codex and all the choices you got to make from that.
As for Prim's question, what army would I like to play; I put together the most likely suspects.
Most likely;
Space Wolves: HQ customization is pretty neat and built on its own (instead of Minotaurs count as) it is a pretty nice codex.
'Nids: I still like the nids and think they are really cool. The new models don't really change much for me in this regard. The original reason I got rid of them was mainly that I didn't want two horde armies for 40k.
Necrons: The new fluff is inspiring, especially when you consider how I thought the last dex was super boring, the turn around is amazing.
possibles;
Vanilla Marines; It's a good dex and again built in that regard it would be fine. Own color choices gives a way to make it my own.
Dark Eldar; There are some really good models in this lot. Then again, I'd be forced to show my army against Pikey and MiJ which would probably lead my entire army to put paper bags over their heads in shame compared to these two.
Chaos Marines; Depending on the new codex, I might be willing to give them a second go. They were my first army, but I need to be convinced.
