Don't forget the Pioneer reference discs.
GGV1069 for NTSC (still available from Pioneer)
GGV1007 for PAL
They have by far the most pure test signals, far better quality than the VE disc, and are the smaller size disc to allow adjustments to be made to the LD player while the disc is in.
You need these if you want to calibrate your LD player correctly using the player's service manual.