It depends. Is this one of those "If your dog and some random guy on the street were falling off a cliff, who would you save" questions, then a person. Unless they were morbidly obese in which case I'd go over too.
I think people are more important, than say, various reptiles and collies I have had.
Having said that, I used to have this german shepard named max. Big, huge dog. Not the brightest, but great company. Anyway, since I crossed the road every day, and he did too (at this point in life I lived out in the country and had no electric fence) he ended up getting hit by 7 cars. He probably did thousands of dollars in damages (but no person was ever injured). He survived, though, and I let him, so maybe I would. I got treatment at the Vet's like Tim Taylor did in the emergency room.
But, as a herp fanatic, my snakes come pretty early on the priority list (well, they did before getting married). At one point I had an emerald tree boa that took me a year to hand train. I still have him, but he doesn't bite. I have never spent an entire year getting an angry person with sharp teeth to learn something, though.
So maybe I do.