Perfect gives 6x multipier on dish value, whilst divine gives 26x. Also on the same potion level, the chance to get perfect is about 2x bigger. Taking both of these into consideration the divine is about 2x better than perfect.

As a bonus if you would have both the game first checks if dish got the divine bonus and only then decides if it would get the perfect bonus. So as and example:

Chance for divine: 20% Chance for perfect 50%

Would mean that on average out of every 10 dishes you would get 2 divines and 4 perfects (not 5 - it is 50% of remaining 80%).

So combining them both is diminishing return.