Lasers are actually on the underpowered side of things. All you need to do to deal with them is make intelligent use of sight lines to get into your weapon's optimal range. I realize that is asking a lot of the cowadootie kids.
Lasers lose any fight in which you are at optimal. Literally every weapon in the game trumps them. If you are aware of where they are shooting from there is nothing they can do to kill you - unless you make a mistake and leave yourself exposed.

Assault rifles are still disgustingly OP and probably always will be.

if a guy with a laser is leading his teams with kills every time I play this game. That means laser rifles are op.

You shouldn't have run away from him
When I use my lasers, I am at the tail end of most weapons max range, this happens to be the most effective range for a laser. So anyone who uses lasers properly may not die much and can get a lot of kills. If you would have gotten closer it would have been much harder for the LR. Also, upgrade your sharpshooter operation and you can at least force them into cover. I use LR it certain maps and scenarios, and I have my Light Sharpshooter skill up, so if you are 60-80m from me then, get cover. If you are within 30m, you probably have the upper hand against my LR, since it is much less effective and hard to aim up close.

The laser rifle is not overpowered, it just has advantages and disadvantages that are not immediately obvious.

Here is a list of weapon ranges and optimal range

The thing is. I already know they good at long range. I cant run period. Once the guy with the laser see you, you die unless its some cover right next to you, then you can hope you make it between or behind it.