In short, if you want to save power go with 5V, if you need longer cable runs or long chains of pixels, 12V is the best choice.
5V
Benefits:
Cheaper and uses less power than 12V, suitable for shorter chains of pixels.
Disadvantages:
Requires more power injection for longer chains/cable pulls.
Due to the lower voltage, the voltage drop will be greater than 12V.
12V
Benefits:
You can make longer chains/cable runs without power injection than with 5V and they are suitable for longer chains of pixels.
Disadvantages:
More expensive than 5V, uses more power than 5V.
Power consumption
As a rule of thumb, a pixel at 100% uses 60mA (0.06A). With this formula: Ampere x Volt = Watt you can find out how many watts a pixel uses.
Here you can see the power consumption of a pixel at 5V and 12V:
| V \ % | 100% | 75% | 50% | 25% |
| 5v | 0,06*5=0,3 W | 0,045*5 = 0,225 W | 0,03*5=0,15 W | 0,015*5=0,075 W |
| 12v | 0,06*12=0,72 W | 0,045*12=0,54 W | 0,03*12=0,36 W | 0,015*12=0,18 W |
