This is a really fun taste test by the Gear Junkie team:
Although they are an American company, and the brands they tested are American, it is worth a read/watch for the entertainment value as well as the info. And yes - they included tinned dog food, with surprising results.
My favourite is still the Look What We Found range - they are not dehydrated meals, but even for someone obsessed with carrying as little weight as possible in an expo sack, they are worth the extra weight for the taste, nutritional value and absence of gluten and lactose (in some of the range).
What's your expo food of choice, and why?