If interested in Italy, then your in luck, as they have started producing supplements for late war Italian theatre. Devil Dogs and Monte Cassino iirc.
After buying lots of FoW supplements, I made a decision to only buy the hardback books they release as generally they will release lots of books in softback, then amalgamate them into a hardback release. The hardback usually has points reductions to entice you into using them. For example take a look at the SS Gepanzerte Panzergrenadier company lists in one of the softback supplements(cant remember the name sorry) compared with the same list in 'Earth & Steel' (hardback version of the Normandy lists). Significantly cheaper points wise and you get extra lists in the hardback books. I am strangely taken by the Beutepanzer company list from 'Earth & Steel' (1940's French tanks used against the allies - it can only end 1 way
)
The plastic shermans recently released by Plastic Soldier compare favourably with the Battlefront ones size wise and detail. I bought some Zvedza Pz II's to compare with my Peter Pig PzII's and the Zvedza ones were quite a bit smaller.
I believe Plastic Soldier will be releasing plastic kits for StugIII/G/H in a combined kit, along plastic Pz IVH. There are also rumoured plans for plastic Panthers and Sdkfz251.
If I was starting out now in 15mm I'd definetely be buying the plastic vehicles for all the workhorse units.
Bill