Well, units, geographical areas and playable factions, buildings or so might not hurt either like more different forts or so.
But it's all completely irrelevant if it does not come at a fair price, I get tons of models code etc. for the 46EUR I pay for the full game, don't make me pay 10EUR for 5 new units because that would make me say "no, thanks". Also since I bought my game from the UK but live in Germany, allow me to get the proper UK DLC because if you only let me access the content for my region I'm not even going to try downloading it for fear it will mess up my game completely, somehow I think that cancels out distribution via Steam...

Obviously chances that I will buy any DLC are rather low, not that it bothers me a lot...