Soldiers: Heroes of World War 2 is in my opinion the best WW2 RTS sandbox there is. Better than Panzers (though I like those too), better than Company of Heroes (Dawn of War in a khaki costume) and better than all the minor games out there too.
It is also better than Faces of War; can't say about Men of War as I don't have it. It has better reviews than Faces but I am still suspicious and don't need to get it when there are so many mods and bonus packs free for Soldiers.
That is essentially what this is - more of the same Soldiers - only HARDER! Some have reviewed it saying that some missions are impossible but if you are a seasoned Soldiers player you will manage. I played it twice and the second time was no problem.
By the way, I paid about £10 for this on Gamersgate years ago. I only just found it on disc here but if you look around (check the DMS forums) you might even find it as a free download.