I will chime and and say...
Situation dictates.
I can think of some situations where I would much rather have a laser on my gun. I don't currently have any on any guns but only because at the ranges I may shoot defensively in my home, if they're in the wash from my flashlight, they're targeted. If I had a slightly larger home I would probably have one on my defensive pistol.
For those that claim that lasers are only good for one given range, well, that's any fixed sight system.
I shoot competitively with a slide mounted red dot. I love them. And to be honest, it's the only way I can reliably see my sights anymore. They take practice and have a learning curve, but they work very well for their intended purpose.
As per @High Exposure 's recommendation, I agree and would say that you should spend the money for a quality piece of kit. For competitive use, I like the Vortex dots. I have a couple of them and they're great for the money. I also have an SRO and it's heads and shoulders above the Vortex's but it's also quite a bit more money. If I was looking for something for a defensive gun, I'd look at a Trijicon RMR.
Good luck.