Who is best

The natural instincts of each species lead towards antagonistic interactions, though individual animals can have non-aggressive relationships with each other, particularly under conditions where humans have socialized non-aggressive behaviors.

A dog and a cat face off. The cat is displaying defensive posture typical of interactions between a cat and dog that have not been socialized.

A kitten and a dog that have been socializing and interact with each other without aggression.

Cats and a dog sitting together.
The generally aggressive interactions between the species have been noted in cultural expressions. In domestic homes where dog and cat are reared and trained properly they tend to relate well with each other, especially when their owner is taking good care of them.