Smarter? Prolly a cat when all is said and done. They are superior predators, no question there. Now as to which one has managed to bond their fate closer to the finest apex predator on the planet, dogs hands down. Cats do a great job keeping small rodents in check and hacking up hairballs. Dogs:
Detect drugs, cancer and seizures.
Help blind people lead better lives.
Find people in distress.
Never cook bacon while naked.