How do you know which Canidae formula to use

. I've been looking at their website, and I see they have 3 different formulas suitable for puppies, does it just come down to flavour?
I would appreciate some recommendations.
I've been feeding my puppy Royal Canin [that's what he was being fed when I got him], but he's been eating his poop

, and I haven't felt too good about the Royal Canin after reading posts here on YT. So I just put the last of it in his bowl, and will be buying some Canidae tomorrow.

