Red dots are better at longer range, but that's not an issue at home defense distances.
Red dots require you to bring the gun up to eye level, while lasers can be used from unconventional positions, like shooting around a barricade. This is very possible in a home defense situation.
A laser will not interfere with your iron sights, assuming your vision can still make some use of them. A red dot has the potential of blocking your iron sights if the lens gets broken or obscured.
Lasers have been known to cause criminals to back off. Red dots have never been documented as having that psychological impact, to my knowledge.
If it's either/or my vote would be for the laser. Crimson Trace offers substantial discounts to instructors, FYI.
My father wears bifocals, and can't focus on the front sight of a handgun. When he shot one of my laser equipped pistols, he remarked that it was like cheating.