I would say Mercenaries 2: World in Flames. Laugh at me all you want. I know it aint a storytelling masterpiece, I know it aint even adequate graphically speaking, but I honestly really enjoyed the game's take on resource management and had a ton of fun buying different vehicles and weapons and stockpiling oil and airstrikes. The trouble is its AI is, well, dog shit in flames--and I'm talking about enemy AI here. You'll be trying to make a covert strike against an enemy camp, but just as you start to move over the hill a truck full of guys drives up on the nearby road and they dogpile out and rush you. The AI is never un-aware of your presence and you can't sneak around, which is all this game really needed for it to be a buy for me instead of a rental.
Crysis has a lot of the same problems, but it doesn't even have the high-level resource management elements. They tried to include stealth elements, but they're so heavy-handed that it's obvious that either the developers tried to make them way too complex and "realistic," so they just never feel like they work, or just flat-out didn't want players to use them.