Personally I like the laser bore sighters. They allow me to sight to "close" before ever firing a shot.
Example, I sighted in my new AR, only I forgot my bore sighter. I spent an hour trying to just FIND the paper with the bullet. The guy next to me let me borrow his bore sighter. Come to find out the scope was WAY off. Bore sighter allowed me to sight in to the paper and within 10 minutes I was zeroed in at 100 yrds.
The only draw back I've found is that most laser bore sighters are only good out to about 25yrds. I've used the Wheeler Professional Laser Bore Sighter once and that laser is MUCH stonger than any other one I've used. I can reach out A LOT further for sight in than with the smaller in chamber models.