Go with laser…
When the hair is visibly dark and there’s a lot (a few dozen or more). Electrolysis would be suitable as well in this case because the end cost would be similar. The more hair there is though, the more cost effective laser becomes. Sometimes it comes down to personal preference.
It may be that the sensation produced by one or the other is preferable.
Or, the fact that when receiving laser, the treatment area must be shaven, while prior to treatment with electrolysis it is required to grow the hair for a few days.
Laser treatments are generally not scheduled as frequently as electrolysis.
Another plus is the fact that regrowth is more delayed than any other form of hair removal.
The skin may have less of an inflammatory response to laser.
But whichever you choose, you have to remember, laser is only going to be effective on hair that is dark brown or black and not fine.
If you have a variety of hair types and colours to treat, or you have some detailing to do, electrolysis will be more appropriate. In many cases it is necessary to treat with both methods!