Which power supply to use for Raspberry Pi? High voltage Low current (10V, 1A) or low voltage high current supply (5V, 2A)? why?
The official spec here
https://www.raspberrypi.org/documentation/hardware/raspberrypi/power/README.md suggests a minimum supply voltage of 5.1V for an RPi2 (and other models). You may get away with just 5V as there is likely some degree of voltage regulation headroom.

You comments suggested that the supply voltage could in fact be higher at a maximum of 12V. In this case the on-board regulation is going to be working hard to bring the voltage down, dissipating a lot of heat and stressing the unit. It would work if it's in spec but it's not a good choice. 

As a rule you want to go for the lowest voltage that's acceptable with sufficient current capability to drive the unit at it's peak requirement e.g. high cpu load and driving peripherals  with a high current requirement like WiFi.

5V 2A is the best choice from your available options.