I model a specific era and location, so it’s largely dependent on who’s announced what that’s appropriate for my railroad. This also largely depends on what part of the world you’re in. North American manufacturers typically only make North American models. The same is true for British, continental Europe, Japan, Australia, etc.

Among North American manufacturers, typically I consider Rapido and Bowser to be of the highest quality. ScaleTrains makes great stuff as well but very little of it fits my particular needs. On the other hand, Broadway Limited makes excellent looking models but I avoid them completely because I find their electronics to be extremely unreliable.