I choose simple. Good white electrical tape (3M or similar) and a permanent, fine line black marker.
You can either wrap it around the cable onto itself, leaving a small tag to label - or if you want a very clean look, wrap it around the cable lengthwise. And, it's far easier to label the tape on the roll than after it's put on the wire.
I've used another option with success, but it's just too much work. Print out small text on the printer, cut it in thin strips with an exacto knife, wrap it lengthwise around the cable and put clear shrink tube over the top. Also, unlike the simpler method above - you have to do this before putting any ends on the wire.