As a new user, should I be working on version 6.10 or 7?

What seems to be the easiest, least resistance, path to get a simple app up and running.

The API for developing UI in version 7 is much more clean and simple. Also, you won’t have to migrate in the future.
So if you don’t use add-ons currently available only for 6.x, I would recommend using 7.0.