You know, it's really weird. I used to change Starr's food about 4 times a year. I mixed it together to get her used to it, BUT she'd pick out the new stuff every single time and spit the old stuff on the floor
I never could tell which food she'd like the best, it was always the NEW she wanted
My girls now get a mixture of Solid Gold, Castor and Pollux, and Blue Buffalo. I feel that if they're used to eating a mixture of different foods (and they're all high quality foods) that their tummies won't be so darned delicate. Never had a problem yet, knock on wood
Good luck, you'll find what they like
!