A plus side of the taser is that it can't hurt the one that is using it (unless the user is really.....), unlike pepperspray, wich can be blown back (by wind) into the users face.

For example, in the UK where the police don't carry firearms, a taser would be a good alternative (together with OC and baton).
Because it's not-lethal (in most cases) and looks like a gun, wich disencourages the criminal to use force against the police.

I (16) don't carry any weapons. But I believe that in The Netherlands (where I live) tasers are illegal. I don't know if pepperspray is illegal.