I tried the following programs Amphetamine, Caffiene. Anti Sleep. I like Anti Sleep best, especially for the new MacBooks with Haswell chips that no longer have a 'Never Sleep' option under Power Preferences. Here's what I like in Anti Sleep:
1) has a auto launch/auto activate on system startup option, great for remote systems, like a laptop, that need to be always on for access. No human needed to activate.
2) Has options to only activate when powered by AC, versus battery, or both. Again, great for laptops.
3) Display sleep can be set separately from machine sleep.
I provide remote assistance to family. When they need me to look at something on their system, I just need to tell them turn on the laptop, plug it in, leave the lid up. They don't even need 'activate' since it is set to auto launch and activate if AC power is on. I can then log in anytime thereafter, even late night. I set options auto launch/activate at startup, activate only when AC is on, and stay awake indefinitely.