"Soldiers: Heroes of WW2" and "Faces of War" are my favorites.
Soldiers: Heroes of WW2
Homepage:
http://www.codemasters.com/soldiers/
Videos:
Faces of War
Homepage:
www.facesofwargame.com/
Videos:
Both of these games are the most realistic physics and damage models you can get in a RTS style genre.
They allow you to pickup and store a ton of different items on each unit and vehicle: (booby traps, gasoline containers, different types of grenades, flares, flare guns, flame throwers, crowbars, crates, helmets, body armor, differenet types of ammunition, knives (to throw at soldiers without alerting others), explosives, metal detectors for mine sweeping, mines, bazookas, binoculars, matches (to set fire to things), first aid kits, bandages, radios, repair kits (to fix vehicles, tank tracks, etc )
What I like about both of the games is you can take your time and move through maps tactically. There is coop as well so you can play along side your friends to help each other out when you run low on resources and ammo. Each weapon has a different caliber so you will find yourself rummaging through abandon vehicles and crates just to find ammo for the weapons that you are using. So, instead of destroying everything in your path you can choose to damage vehicles and equipment in such a way that you will be able to repair and extract inventory items to rearm or reuse.