I think I would choose The early to mid Middle Ages. The wide variety of well made melee weapons and the high availability of chain mail armor would make slightly easier to survive close up encounters. Another reason, it'd be... well... FUN. I'm not just taking survivability into account.
1. Better made clothing and blankets
2. Better medicine
3. More scientific knowledge about everything from human fitness to combat and survival
4. Larger and more stable armed forces (not that this would help much)
6000 years from now. Everyone will be equipped with optic blast systems that disintegrate zombies. All facilities will be zombie proofed, as they are holographic energy walls. We can fly on our hover cars that run using human will as power.