I have both a Crimson Trace and a LaserMax. The specs for the laser on both units are identical. The main difference is the on/off button location. I have attached photos of each.
The CT has the button on the front of the grip, under the trigger guard. CT says all you have to do is grip the gun and the finger on the button turns the laser on. Mine is on a Ruger LC9. It is a small gun and with the flat magazine floor plate, I can only get two fingers on the grip. The first problem is the button sticks out 1/4 inch. One finger sticking out that 1/4 inch further does not feel good to me, with only two fingers on the grip. I ended up gluing a 1/4 inch thick piece of rubber under the switch, to eliminate this problem. The other problem is the laser does not go on every time. If my grip does not contact the button just perfect, no laser. The only way I can guarantee it goes on every time is with a "death grip". CT sent me a replacement laser, as I complained to them about the issue. They said it could be a bad switch. The new one arrived with the same problem. Another problem is if you don't want the laser on, you have to adjust your grip, so you don't put pressure on the button. Since I have a problem with the CT laser turning on, I do not have this issue as all I have to do is slightly release my death grip, and the laser goes off.
The LaserMax is on my Shield 40. The on/off button is located in front of the trigger guard, under the slide. The Shield is almost the exact same size as my LC9. I can only get two fingers on the grip, but don't have the switch sticking out issue. You push the button on with your trigger finger. It stays on until you push the button back from the opposite side. If you don't want the laser on, you just don't push the button. You do have to think if you want the laser on, but with practice this should be second nature.
The CT has been on the market the longest and has sold by far more lasers. With the issues I had with my CT, I prefer the LaserMax. I bought the CT a year ago. I paid $160 at a local gun show, which was cheap, at that time. I bought the LaserMax four months ago from EBay, $86 including shipping. The seller was fuddlebucks. It came with the full LaserMax warranty.
Bob
Crimson Trace on my Ruger LC9. Showing step out of the switch and the rubber block I added. The nut/screw is a trigger over travel stop that works great.
LaserMax on my Shield 40. The trigger guard is much smaller than the LC9's trigger guard.
Showing the Lasermax frame on my Shield. It takes up no more space than 1/16 inch, same as the CT Laser.