Mmm, flicking through the cards I'd say that ones that are a bit more interesting/show off the games features more would be:
fighter cards (then again, I'm new to wargames, maybe the whole abstracted air control mechanic is a common thing)
political commissar (shows off the C3i system a little, shows off the theme a bit more concentrated than 'artillery')
command and control (same as above sans theme, also, I love this card, it seems so great for screwing up an opponents plan/extending your line)
Not that there's anything wrong like artillery, surely it just shows how good your game is when peoples complaints are on the line of 'show it off more'.
