For a year we had all three on Nature's Variety & we fed them 1/8 cup twice a day and mixed in green beans & a touch of wet food. They get a treat twice a day.
We are now testing Orijen & Fromm and we tried doing a 1/4 cup a day without green beans, but a touch of wet. Well I measured what they left in the bowl afterwards and it was 1/8 cup, so they seem to be eating the same amount as before!