I'll start off by saying I have been in the hobby for years, but haven't purchased from many/most of the plastic passenger car lines - only Concor and Walthers. Right now I own a brass California Zephyr made by Kumata and imported by Challenger/High Country Brass/Oriental Ltd (all the same cars, just different importers). I also own Walthers Superliners and Concor Material Handeling Cars. I once owned Concor budd streamlined cars and Concor superliners.
Here is the deal with plastic passenger cars ... for years, the choices were limited to only a few kinds and brands, mainly because the tooling was too costly offer prototype correct versions of so many RR passenger cars. Railroads of the 40's and 50's and earlier had so many unique passenger cars all constructed to different plans and specs. Literally just about every RR company had a different type than the next, and there were many companies back in the early days. Most of the passenger cars offered in plastic were "bogus" because the plastic cars made usually only represented one correct prototype, but manufacturers had to paint them for others to sell enough to make money back from the tooling/molds. So for years there have been only a few railroad passenger trains which could be correctly modeled from plastic passenger cars.
Lately, things have changed in the area of plastic passenger cars. Manufacturers have sensed that there has been enough demand to offer new passenger cars and make them with more detail and fidelity, but at a higher cost naturally. This is great because in the past, the only way to correctly and accurately model "most" passenger trains was by buying brass at prices ranging from $100 to $350 per car! Now we have more options of streamlined cars and now new heavy weight cars from Walthers and Broadway ltd etc.
Frankly the choices haven't expanded as greatly as could be because a bunch of the newer improved plastic cars are Santa Fe, duplicating models already on the market for years from Athearn (shorty cars) and Concor (scale length cars), but they are greatly improved and much needed ATSF modelers. Walthers offers Budd cars, but mostly represent Amtrak "heritage" era cars with skirt removed etc. Walthers also offers Pullman Standard cars - one of which matches closely cars run on Rio Grande's Prospector.
But Val, here is the dilemma. You may have only one choice in brand if you have found "correct" passenger cars that match your CNR or CPR heavyweights. If Walthers newer cars match those, you are lucky!
As for brands, hopefully some folks can shed more light but I can comment that Concor passenger cars were "lousy" in my opinion - low detail and cheap running gear like trucks and couplers. They required allot of extra work to make them into good looking and running models. I have handled Riverossi cars, they look much better but the running gear is still old tooling and needs some improvment. I have no experience with IHC, but my impression is that they are "old tooling" and are really showing their age. I have never been impressed with other IHC products, for the same reasons. But if IHC is the only match for your needs, I'm sure they can be made to work for your. Just keep in mind they are old tooling and may need some attention if you want a little more detail etc.
