i think fast ones are always cooler for games and slow for real life because that way you stand a chance, but it varies in movies. In movies, fast ones are usually in gory slasher films where you're on the edge of your seat. Slow movie zombies are more phsychological horror. An unstoppable threat that will get you eventually, no matter what you do.
If I had to think of an uber zombie, it would be the ones depicted in the trailer for the new movie "crazies". They look normal and act somewhat normal, but they are plotting your murder. It's like fast zombies, but smart and you can't tell if they're a zombie or not.