Of course, if we assume the colors represent something real rather than just artistic license, then you'd want to have blue beams rather than red, because blue light is higher in frequency and energy than red light. So a blue beam would be hotter and more powerful than a red one.
However, that clashes with our psychological expectations; we see red as a "hot" color because we associate it with fire, and blue as a "cool" color because we associate it with water. So FX artists tend to get it backward, using red beams to connote higher power than blue beams. (Case in point: in the '09 film, the hand phaser's beam is red on kill, blue on stun.)