My choice is neither. They make you look at the wrong thing!
You should be looking at the front sight!
These things slow you down. Seems like they would help, but they don't.
Short cuts to skill usually don't get you where you want to go.
I find that most of the time people make blanket statements, they are just wrong. They don't "make" you do anything. A lack of training and a reliance on the laser over proper tactics and techniques "results" in one looking "at the wrong thing".
I have been using lasers for around 13 years. I primarily train and shoot without the laser but in low light, when using the laser, I am substantially faster than with iron sights. People use the laser in the day and say it's slower...No ****. In the day you can see your sights well. In low light you can't.
One could argue for night sights. I could go on and on about low light, it's effect on vision, especially depth perception and close range vision making focus on sights while still maintaining minimal perception of a target, particularly a living one that is moving and reacting, but I'll make it short and sweet. It is EXCEEDINGLY difficult (note I don't say impossible...blanket statements are never good) to see night sights in a reactive low light environment. A laser, however, works. It just plain works...Well.
Now, as with any piece of equipment, training is key. Equipment is not a substitute for training. That said, good training and good equipment makes for a good result.
A light is (in my opinion) much more important than a laser. They both, however, have their place.
Now, as to some technique. I train and teach that when presenting the handgun, the shooter is always looking for the front sight, and always presenting the gun in the same manner (ie: isosceles or weaver stance with pistol in line with eye). As the handgun is presented to the target if the shooter sees the front sight (as in day light) then the focus shifts from target (ID) to sights. If the shooter sees the laser (usually in low light or indoors) then they are able to maintain a target focus for better evaluation of hit effectiveness and continued threat identification, while making issues of sight alignment and sight picture moot. As the pistol is presented into the field of view, the shooter keeps both eyes open and looks through the pistol (which is a see-through blurred image) at the target. If the laser dies, it's a simple transition to sights.
There are multiple drills that can reinforce this sights/laser transition.
Skill is good, but skill going up against skill and good equipment is gonna get smoked. Every. Time.