Lasermax are good, albeit pricey. The price for Crimson Trace has come down to earth in some cases,...however, be aware of the activation "button".
CT's have a natural grip activation, while Lasermax has come close. It is an aftermarket modified guide rod. There is also Viridian.
The reviews are positive, my co-worker has CT's on his M+P .40, and Lasermax in his "G" gun. I like the CT's better, however, the Lasermax has its' act together, I would just test drive them all first.
Seems a wee bit bulky, in the Genesis config. But the guide rod stuff is very good.
Good shooting.
tw