@Fa5t3r - I would try a wide range of different tones when recording and play them back to see what goes over the best and what projects the image you want people to hear. Remember that some people may be going to hear this message over and over again depending on how often they have to call you so you want it to be very pleasant and not at all irritating.
6.) Hello and welcome to the John Doe AG - Your agency for sample products. Unfortunately, all lines busy at the moment. Please try again later or wait just a moment. Thank you, your John Doe team.

If you’re out of the office, a voicemail greeting will essentially act as the first line of communication between you and clients or potential clients. So of course, this could be a great opportunity to add a hint of personality, while of course still remaining as professional as possible. That doesn’t mean you can’t have some fun with it!
Tone - select the right tone for your business brand. If your target market are young millennials, then the script would most likely include some slang words, be quite laid back and the script would be recorded in an energetic tone. If you primarily service the business market, then the script would be more articulate and recorded with a more professional tone.