In addition to NecroYawgmoth, Griselbrand being a 7/7 Flyer, Lifelink is also important because he can disregards his ability and just put the game out of reach vs Burn and its variants on fast-aggro.
You'll just get into situations where recurring FKZ wont immediately kill your opponent, and in those situations anything is better than FKZ.
Altho' honestly if you want to play with 2 Dread Return, 1 Griselbrand and 1 FKZ just do it game 1 and SB it out game 2, as long as you have the SB space to converge into your post-board plan then what you choose to play for game 1 isn't a big deal, altho' I'd never play FKZ game 2 vs hate for certain.
The reason that Griselbrand is hands down the best DR target is because he's a stand alone threat at 7/7 Flying, Lifelink and he draws/dredges the deck out into a position where you're opponent is Mind Twisted and can only top deck Swords to Plowshares Griselbrand and die to Zombie Tokens and Ichorids, Terminus and get attacked by Ichorids who leave behind a board full of Zombies or Tormod's Crypt and die anyway to Griselbrand and Zombie Tokens. Griselbrand ensures your opponent is facing "power overwhelming," because there's just no way to McGiver your way out of that ass beating.

