One of mine is like yours, very choosy!
If she can choose she'll eat just cooked chicken & the small gravy bone biscuits.
She used to eat Royal Canin Yorkshire but I'm wondering if they've changed it again as all mine have suddenly stopped eating it.
The one she really will not eat is the one the vet prescribed for her (she has IBS) Hill's Science Plan W/H.
One has James Wellbeloved as he has allergies, the others were on the Yorkshire till they've gone off it, but they will eat the James Wellbeloved & also Royal Canin Mini Adult.
But the one food they will pinch & eat, that they're not supposed to, is the big dog kibble I buy from my local animal feed merchant for my Skyes!
Cesear gives all my lot bad diarrhea