I prefer walking--as in the original Night of the Living Dead
, where some were stiff, others (like the 1st graveyard zombie) could pick up the page and swing arms when close to a victim.
It is easy to understand why films such as the 2004 Dawn of the Dead
remake used running zombies to turn up the threat level (essentially Aliens
-flavored chase scenes with zombies), but you lose the morbid sight of stiff corpses when they move like 'roided track stars.