In my experience, whether it be Arctic or Baltic or Russian or Northern...almost does not matter. The goal is to get plywood from a slow growth cold climate forest which yields a dense stable wood.
One product you never want to use for a train platform is Pine anything. No guarantee on how bad it will warp.
The best value in plywood for a layout in this market is a 3/4" (23/32") Birch called "Shop Grade". It has plugged veneer but perfectly solid core. Paint grade.
There is a some what popular HD product called "Sandy Ply" which is pure Russian Roulette. OK for a dog house or your in-laws but a real gamble for your RR.
IMO, the best value in 3/4" sheet goods is Advantech manufactured panels. Period.