Williams seems to be coming out with more accessories of late. They now have dump cars, a cop and hobo car, street lamps and now this operating billboard. They are also expanding their scenic products line. I would venture to say that there will be more to come.
Kader/Bachmann/Williams is the only manufacturer with their own design team and
factories. This appears to give them a distinct advantage over the competition. This arrangement of the total operation approach under one roof eliminates the "middleman" and, allows us to buy F3 and GG1 O gauge engines for under $200 at discount retail. I have found that the quality is top notch and the reliability is almost always rock solid. Except for the electronics I see no difference in their products when comparing them to the other brands.