The only one I have used is the Rec-T-Fire system which is made in Quebec.
We did a review of this product in the November issue of Pointblank Magazine.
This system is quite unique in that the laser unit is universal. You have the choice of breech loaded cartridge blanks or brass muzzle spuds. The laser unit is then inserted into either the muzzle spud or the cartridge blank.
I found the muzzle spuds to be the most accurate. The cartridge blanks would be great for a hunter in the field as it makes it impossible to load the rifle while the bore-sighter is in use. However the accuracy of the cartridge system is dependant on the chamber dimensions. Loose chambers will result in bore-sighting innacuracies.
I found the system very easy to use and quite accurate (bore spuds). On one occasion, no adjustments were required after bore-sighting. The rifle shot to POA at 100 yds. Never seen that with a conventional bore-sighter.
The Rec-T-Fire system can be used outdoors but it is best indoors. I have about 15 yds in my basement which is pretty close to the near zero for most calibres.