Red Dot V5

The red dot's construction allows the use 2xAA battery. That's a massive amount of power resulting in long battery life.

Moreover, finding replacement batteries is as easy as it gets.

Just 3 buttons. Increase brightness with the two on the sides, switch color with the middle one. Turn off by pressing the two side buttons at the same time. That's it.

You can choose between red and green reticles. Not that it makes a difference but it's cool and you can mix it up if you get bored by it.