I picture a big heavy dog with a temper... Of the 2 I'd go with the 9 if you're sure you won't get a bear interested too. Actually, I'd probably go with a 40 or 45 but that's a different story.
I'd shoot the first one going for you...
then again, how often does one hear of humans being attacked by packs of wolves? Is this even worth planning for? Maybe more likely that you'll be attacked by a methhead?
But be safe out there...