Cf: The grass is always greener on the other side of the fence (Am., Br.). The grass is always greener on the other side of the street (Am.). The hen of our neighbour appears to us as a goose (Br.). The next man's cows have the longest horns (Am.). Our neighbour's cow yields more milk than ours (Br.)
Русско-английский словарь пословиц и поговорок. Академик.ру. 2013.