Again, it all depends on a lot of factors. Do you want it for outside or for inside? Does it need to withstand cold/high humidity levels? Is it underwater? And so on.
We will try to expose few solutions with their advantages/disadvantages.
- no need for a special reading device
- can be printed anywhere
- if a tag breaks, just print it again
- if printed on paper, they can't withstand too much natural stress (rain, sun, humidity)
- needs light to be scanned
RFID tags (125kHz)
- very durable
- cheap (less than $0.15/tag)
- can be reprogrammed (if needed)
- fast scanning comparing to QR code
- can be read in any light level
- needs a reading device, some of them have the code printed on them too but that wears out and you need to manually insert it