Which would the fastest way to get this task done?

 

I can't afford cannoning

About even as combat familiars cant hurt them so id say slayer dungeon.

Turoths in the chaos tunnels are much more close together. The slayer dungeon may have more total turoths if I remember correctly, but having monsters nice and close is much better. The only drawback to chaos tunnels is if you get randomly teleported to the bronze dragon room on your way to turoths, which isn't too bad if you take the proper precautions. Also, cannon doesn't do anything to turoths and kurasks.

The fact is that cannon doesn't hurt them.

Another fact is that Fighting familiars do hurt them! (steel titan <3)

 

Thus both locations are about equal. I prefer doing them in Slayer dungeon because there is such a handy teleport there and thus I can piety them (wearing proselyte and fally shield 3), recharging prayer at Ardougne monastary when I run out and be back in killing in under 1 minute. For chaos tunnel location it would take longer.

 

Since you don't really have good fighting familiar and neither you can't piety them (I still suggest using +15% str).. well, go to the one that is more comfortable to reach for you (should be slayer dungeon especially if you got rings of slaying)

The best place is actually the Smoke Dungeon (near Sumona). Very fast to get there, assuming you have a Slayer Helmet and rings.