Roco do make some beautiful wagons and loco's, albeit usually European Outline and HO gauge so not so interesting to the average UK modeller. But I love the attention to detail and build quality, I've got some (not of those) and passenger carriages in my collection as well as some of their diesel/electric loco's, the latter are incredibly smooth runners and again have stunning build quality. The only downside is the cost is usually on the higher side, but I guess you get what you pay for. One of my favourite ranges they used to have (not seen any around for a while) were the military themed flat wagons with tanks and other vehicle loads. Roco used to have a range of military models called 'minitanks' as well so the train wagons were a natural extension to that range.
Happily collecting things all my life...