If it’s legal in your area, then both.
Some situations would be solved by the threat of pepper spray, some by its deployment.  Some situations may require the threat of a firearm, and – as much as we hate to admit – some situations do require the use of the gun for personal protection.

It would be a shame to use a gun where pepper spray would have been effective.  It would be just as regrettable to only have pepper spray where a gun was necessary.

Unfortunately, the gun option isn’t really possible here in Canada – unless you’re at home or out hunting.  Even then, you would still be treated like a criminal.

What’s most important is ensuring your own safety – and unfortunately that does sometimes mean protecting yourself from overzealous, bleeding-heart, gun-hating prosecutors.  Actually they are equal opportunity in prosecuting your inherent right to self-defense.  Just try protecting yourself with pepper spray, a baseball bat, a baton, a knife, or even a belt – and you’ll be pulled into court for harming the poor, helpless criminal.