Single and Double Sheathed Boxcars.
The original road offerings were pretty limited, they pair period-wise with all the Reefers, and when they are ready, they go with the 2-8-0 which everyone agrees should be the first locomotive.
Id buy a ton to get an assortment of roads I like - Frisco, MKT, MoPac, Rock Island, Rio Grande, etc. From SHS, the ATSF are impossible to find.