For the standard Feldgrau uniforms I use the Humbrol "Slate Grey", which has a nice grey-green hue. If you are doing Jaegers, then use a mid-green.
Note that for uniforms exact hues are not important, not in my book anyway. Different makers, different batches of cloth, the effects of the sun and repeated washings always changed the exact colours. Also in Germany, the use of "Ersatz"-material caused an even more motley appearance in teh late-war years.
For the German field tunic, I always use a mix of Tamiya German Grey XF-63 and Humbrol RC 404. For Jaegers and the green on A7V's or Beutepanzers use Tamiya Field Grey.