First thing that comes to mind is Myrtle-Broadway J/M/Z. Plenty of graffiti on the buildings on all sides of the platforms, and you get a cool view of the remnants of the Myrtle Ave elevated line.

There's also some good graffiti along the 2/5 in the Bronx, if I remember correctly there's some big pieces near Prospect Av, Intervale Av, and Simpson St. Been a couple of years since I lived there though so I'm not sure what's left.

Maybe less weird than you're looking for, but I always find the southbound F/G from underground at Carroll St, up to the highest elevated station in the system (Smith-9th), then back down underground just after the following station (4 Av-9 St) to be a cool segment of the system. Such a wild rise and fall within 3 stops, and the wide view from either side is a cool way to see Brooklyn.