Just purchased the Atlas Trainman 60' passenger cars in Grand Trunk Western and thought I'd compare them to my set of MTH premier cars.
First picture is Atlas. Second pic is MTH. In the other pics, the MTH car is on top. MTH car is from the 20-4079 Premier 70' Madison car set, cataloged in 2006.
Observations:
MTH coach has ribbed roof, Atlas is mostly smooth with fewer details.
The green on the MTH is "greener" than the Atlas, and the finish is glossier. The stripes are more yellow on MTH, more gold on Atlas.
MTH has 6-wheel trucks, Atlas has 4-wheel.
MTH car is about 2.5" longer (70' car vs. 60'), and it is noticeably heavier.
MTH has more detail on the underbody and on the ends of the cars.
MTH interior has figures, Atlas has none.
Sides of Atlas car have more rivets.
The Atlas handrails are thinner.
MTH has crisper graphics.
For the roof design, trucks, rivets, and colors, I can't say which cars are more prototypical.
Overall, the MTH cars are far superior, in my opinion, especially since a set would be less expensive than Atlas. Considering that the Atlas cars are about $100 each, I'm a little disappointed, especially after waiting 15 months for them to arrive.