I too have been watching Commander - The Great War for a while. I like the stuff that the Lordz Studio is putting out, even though I didn't get Panzer stuff.
Since, I take it yoiu are just worried about what order you are going to get these titles, and if you haven't played a WWI game in a while, maybe CTGW is the way to go for now.
PitF looks nice too, but as with all CC titles it will take a while to shake out the same old bugs, and me thinks they are going to have to re-code some of the maps because the tanks are beeger and this was not taken into account on some of the tree/hedge lined roads.
Also, if you were looking for multiplayer in CC, I suggest to wait awhile, and see how this goes with this title. There are some players, that just can deal with singleplayer no matter what improvements they make to the AI or pathing, etc. There is a precentage chance, that multiplayer will remain thin (for CC type games), no matter what Matrix/Slitherene does to enhance it.