Ah, yes, the old which-format-do-I-use question.
This is often the second question I get as a personal historian, right behind "What is it you do exactly?"
As a writer by trade, I'm partial to the written word. Books, after all, have been around for centuries. Your ancestors are much more likely to deliver their stories in the form of old letters, diaries, journals, documents and articles clipped from publications than as audio or video records.
The written word, even though most of it is currently produced on computers, is less prone to succumb to the advance of technology. Music in my lifetime, for example, has gone from shellac (78s) to vinyl (45s, LPs) to magnetic tape (reels, two-tracks, four-tracks, eight-tracks, cassettes) to CDs to PCs (MP3s, WAVs, etc.) to iPods. Video has followed a similar path (remember Betamax?).
The truth is, though, that there's nothing quite like hearing a familiar story told in the familiar voice of a parent or grandparent. Even if you've never met a person, hearing their voice or seeing them on video, gives you a perspective that is simply unavailable in print.
Fortunately, most of my family history work involves interviews, which are recorded, transcribed and given to the client. In addition, I'm working with a local videographer so that we can provide the best of both worlds: I create a written work that provides the detail and depth that only a written work can while my video friend records the interviews and edits them into a professionally done 20-30 minute video.
In any personal history project, recording stories before they are lost is the No. 1 priority. Just about everyone has a sad story of how they always meant to record so-and-so's story, but they were gone before they could get it done.
So, what are you waiting for?