Yn 560 11
I have the Mk I and it's a great manual flash, the Mk II improves on it with an LCD screen, greatly simplifying it's setup. There were some issues with early Mk I's that I've not seen mentioned once with the Mk II's.
Personally, I would not take a thing Ken "his name really shouldn't be mentioned in polite company" Rockwell says as gospel. If you want great advice on flash photography, check out the Strobist. Also, for a checklist of useful flash features and a brief review of the Mk II, checkout one of the recent videos by "ThatNikonGuy" on YouTube.