Crimson Trace Laser

I prefer the front mounted ones because the point of impact (left/right) will always be centered. If the laser is mounted 1/2" to the right side, it will only meet the path of the bullet at one point. Point of impact will be slightly left, then dead on, the slightly right beyond that point.

I'm left handed, so my thumb covers a side mounted mounted laser when shooting.
Sick with Crimson Trace only. Cheaper brands don't hold. They move around with recoil.

Thanks Dawg

Activation - the front or rear activation buttons are great. The laser comes on as soon as you grip the pistol. IMO, I'm not a huge laser fan, but work at a store that sells them. I wouldn't buy a laser that didn't activate that way. If I remember correctly, the side activation models are the older Crimson Trace design.