This is hard. If I don't like it, it would never be on my layout. I'd rather have plywood or more track. Not the best photos; wrong device. Still learning this ones camera, which is clunky, but not too bad. I miss my old AL-1 and developing real film though.
This factory used to be an AF talking American Flyer City Station with timed stops. The timer still functions and I use it a lot, so I guess it wins "Best" by default (it actually controls the el, not the lower lines.) It was going to get tossed until I nabbed it (a freebe) No roof or doors (still no door to enter as is 
) and I never liked the green/yellow windows on the station much, but they look "right" to me as old factory windows, so I never bothered hunting parts (now Lionel parts for thier repop)
The fav. on this layout is stored on another device ... so more later.
My all time favorite is my childhood gantry and launcher(& pw car) Enough so that once the WB/Looney Tunes train was done, I ended up with this fun little layout to eat up more "space" 
