It really depends if you are more comfortable with WED or Blender ?
Blender :
If you know how to model, unwrap in Blender go for it, you have total freedom.
Lightmap import in 3DGS is not easy at all , so you'llhave to use real ligths and perhaps some rela time shadows.
WED :
It has some BSP restrictions, but it will produce lightmaps for you. If your models will be simple go for WED.
But when buidlings or stuff is complex go for Blender that have all modeling tools you could need.
Google Sketchup :
For buildings it's powerfull and easy ,fast (you(ll have just to dig some internet tutorials on basic modeling). you export to Collada, then import Collada in Blender than remove any duplicated vertex, perhaps clean geometry than export to FBX or Ojb format , than import in MED (yes it's some more complicated).
Last edited by ratchet; 01/13/13 13:11.