The ADDC is the easiest choice Vicks. Probably the cheapest, very high level of security for the riders (medical assistance etc etc).
Its in your back yard, you can train as much as you want, for most oversea's participants the soft sand is the most intimidating and yet you can practice every weekend as much as you want.
ADDC and navigating, not so difficult as you have the roadbook and the GPS and tracks to help you. People rarely get lost at the ADDC. Since there is a lot of Off piste riding the GPS will give waypoints and CAP headings.
Somewhere i wrote a thread about my first ADDC, back in 2006. it's doable and its a blast.
"If at first you dont succeed then skydiving is not for you."