A laser sight is a tool and nothing more, if you are not well grounded in the basics of shooting it will not help you. It's only real use is when it is to dark to see the sights and by using it you risk showing your position. Spend the money on real practice time and get good at using your iron sight before adding a laser. If you are already a good shooter and not looking for a crutch, the crimson trace has as good a reputation as any I am aware of.
but when your wife want to buy one for you I can't said no!
Sure you can say no. Tell her you would like to spend the extra money on spare magazines, ammo, another gun (maybe one even for her) or on a training course. But if you're set on a laser, CT's will be fine.
I'm pretty old fashioned (conservative) on most gun related subjects, but this is one subject which I differ on with the old gun hands who pooh-pooh the laser. I have Crimson Trace Laser grips on three compact self defense handguns, and a rail-mounted laser on my G20 (10mm Glock). I do not buy into all the mall ninja crap, nor do I believe any of the advertizing hype. But, I do see a practical use for lasers as dry-fire practice aids, and if they do light up in a self-defense scenario, so much the better, because I may not have my eyeglasses and cannot focus the front sight without them.
What I do not do with a laser is practice live-fire, other than to confirm that it is still zeroed. It isn't necessary, and I always want my default aiming method to be the one that does not rely on a battery operated device. If you always do this, the laser can not let you down in a pinch, because you pretend that it will not work when you need it, anyway. If it does work, fine - the dot will be on the spot you are aiming at, and you can use it or ignore it, as you please.
In reality, it probably will work - mine have not required battery changes, yet, and the oldest one is at least two years old.