I used C4D but looked for other apps. I tried the trial versions of 3Dmax and ac3d , the free packages ppmodeler, wings3d, anim8or and blender (no 3ds export), but there are some more on the market.
Wings3d can convert 3ds to A:M mdl files but can`t export UV maps,
anim8or is the best free program I tried.
Yes I`m interested in converting models for use in AM but I think the problem always would be the high patch density of the polygon models.