I noticed my guy's love krill, they love to play with the pieces as they sink and thaw, I feed them a really large variety of food, two kinds of pellets, F.D. bloodworms, F.D. brine shrimp, F.D. krill and Betta flakes.
Just remember to pre-soak your pellets and your F.D. foods in a tea spoon of aquarium water for a couple minutes, it makes them soft enough to eat.
I think one of my Betta's, my younger one, is a picky eater. But I feed him what I feed the other's and if he doesn't eat it then..., he'll eventually get hungry and pick it off the gravel.
I'm all about tough love for my Betta's and spending for different kinds of food.
As jmtriro01 said they will eat when their hungry!
I never tried the garlic thing, but lots of people swear by it. Hopefully someone who uses it will come around and tell u.