Barbarian fishing is a way to fish you learn from the barbarians near mithril dragons entrance. It let's you fish without tools to get small strength xp while fishing. It would only be decent for strength xp if you intended to get 99 fishing and that was your goal because the strength xp would only be a minimal bonus. PC would be much faster if you were seeking strength xp.
I like PC because you gain strength exp while doing it and you also get it as a reward.
Also you make lots of money if you are getting a lot of exp, and I also find it a little less boring if you are going with a clan as you can talk, etc... to pass time.