I'm with WK...it's depends.
My most used for trout fishing spinning rod is a plain 6' L fast rod. I'll catch all the little guys 15" and under with it. Rarely do I use my 5' or shorter rods. 6'8" ML dropshot rod for other applications like float and fly or slip sinker rig. Then the 8'6" rod or 9'6" for wading, casting istance, and other river fishing.