Hmmm... thats a tough one. I like em all. Depends on the situation really. If I am going tank vs tank... either the T34 or the Tiger (and the Tiger is only if I think there is another Tiger out there).
If I am not sure what I am going to be up against, I will roll out a Panzer. If I am taking down a town... the Ostwind. Recon, sneaking a V Base, or fast fire support needed... the M8. Running GV supplies... Jeep! Running troops or field supplies... M3.
For AA, I am taking the M16 more and more these days.
Sometimes I will up the Sdkfz 251 just for S&G's... or if I think I may need to drop a building or 2 with the rockets while taking a town... but they are slow and the MG's are puny.
Never really used the Sherman, since I am usually in Mid War.