what do you consider good ??? Greek food on the whole is of excellent quality... if you mean English then you may do better S/C where many of the bars sell English style food,
i was in kos earlier in the year the food (half board) was brilliant but no chips or burgers/fish fingers or the like
Butlins at Bognor do good all-inclusive deals with mainly "English" food. They do a variety of other options (curry, spag bol etc.) if you like variety. The swimming pools and kids club are as good (if not better) than any on Kos without the bother of having to learn Greek or German.
Have a look at the reviews for Kalimera Kos Hotel and Club Akti. You can use both and eat in either hotel. The Akti caters more for children at meal times, and is more child orientated than the Kalimera. It really depends though on what you want to pay any deals you can get.