Zombies BY FAR, as others have noted their aiming despite looking like a drunk shootout tends to hit far more often than their counterpart. (For christ's sake I've seen rocket launchers zoom by me while I wasn't even paying attention) Whereas no matter how hard I try a magnum always tends to hit me from some zombie a million miles away every time
Design wise, though the J'avo mutate, most of these look too samey whereas the zombies get a lot more variation ranging from Zombies, Zombies with weapons, Zombie Cops, Zombie Dogs, Bloodshots, Whoppers, Shriekers, (I'm positive the one that turns others into zombies with its blue gas was manufactured but it fits more into the zombie catagory than the J'avo one)
Finally to me it feels like J'avo act way too dumb with their taunts and constant yelling whereas zombies just go and attack you in numbers RUNNING!!!!
--- "A good essay is like a mini skirt its long enough to cover all the important stuff but still short enough to keep you interested"---