I just switched my corso pup from diamond naturals to TOTW, simply due to them being made by the same company and i wanted to see how she adjusted to grain free which she did just fine...however i will be switching her to a different brand due to the high calcium and phospherous in TOTW, toooo high for a growing pup IMO. My English Mastiff eats Fromm 4 stars (frommfamily.com) and IMO it is a higher quality food then diamond foods (TOTW). It is made in one single plant and is a small family owned company.
Anyway my pup seems to enjoy the TOTW. Also as far as glucosamine, you are best off supplementing that into a large dogs diet. While many dog foods include things like glucosamine, omega 3's etc..they are hardly enough to make a substantial differance. Glucosamine and fish oils are all available at your local heath food stores. I supplement both of these into my dogs diets.
EDIT: Just noticed in your sig sais you have an English Mastiff...stay away from TOTW unless your dog is older then 2..And this comes from experience, feeding a high calcium phospherous ratio food to your pup could cause skeletal problems. My Drake developed bone spurts in his shoulder from feeding too much large breed food containing high amounts of calcium....