People have short attention spans these days, and you should always craft your communications for the lowest common denominator with something as universal as your voicemail.
A well written script is the cornerstone of any great on hold message. It must capture the caller’s attention, so they remain engaged while navigating menu options or waiting on hold. The script that callers hear can set the tone for the rest of the conversation. It should also be in line with your goals, which can be broken down to 3 main objectives. It can be to inform the caller, promote the brand or product, or just entertain the caller. Most of all, it has to be engaging.

a standard greeting as per Option 5 minus the mailbox user's name, followed by the fixed system prompt, "Begin speaking after the tone, then hang-up when you are finished or press any key for further options."
d. Utilizing Ambiguity Over Clarity: When setting up your voicemail greeting be direct and to the point. Tell callers your information, a brief greeting, and direction—i.e. “Hi, this is Jim Shamalam (from Iron Industries). Sorry I can’t take your call right now. Please leave your name number, and a brief message and I’ll get back to you as soon as possible. Thank you.” This is ideal, as you inform callers and let them know what they should do to ensure a return call. A lack of direction can lead to callers leaving incomplete messages (lacking contact or other information) or even callers hanging up without leaving a message altogether.