Timber is fed home cooked meals, but Leather is fed Pets First. In my opinion, it's the best brand you can get. It doesn't have any corn flour or corn based products, has only vitamins C and E for preservatives, has real veggies added, the same quality meat that is fed to humans, no bi-products and it is great for dogs with alergies, like Leather.
This is info on the type Leather gets:

Our Chicken and Rice LITE diet for dogs is a premium blended diet. It is suitable for older dogs that may have overweight issues. It is also suitable for big boned dogs that require less protein and fat due to their lower activity levels.

An excellent choice for dogs with allergies to corn.

Formulated with chelated minerals to aid with adsorption and a balanced omega profile to maintain a healthy immune system.

As good as it is, it cost fifty dollars!