For control panels I always use stranded wire because of the vibration factor of the joystick and pushbuttons.
For those that need wire, Hosfelt Electronics (
www.hosfelt.com) has 10 different colors of single conductor stranded wire in 16, 18, 20, 22 and 24 gauge in either 25 foot or 100 lengths. Prices are reasonable and the normal colors stocked are Grey, Black, Brown, Orange, White, Purple, Red, Green, Yellow, and Blue. They also sell lots of different types/lengths of power cords.