I think Stumpster hit the nail on the head, everyone learns differently.
The Kayak Roll was the key for me. Though I have a good hip snap now, I had a hard time learning the C to C in the beginning. The Kayak Roll teaches the sweep and body rotation, which naturally results in a hip snap. I didn't have to think "hip snap", I only thought about watching my paddle slice through whip cream as near the surface as possible, for any given situation. Another person may prefer to think "hip snap" when learning though. (Stumpster's point.) Less flexible, older people for sure, have a easier time learning the sweep.
With that said, I watched EJ's equally when learning. Once I had the sweep down, I used EJs drills to learn every other type of roll, and of course a good brace. EJ's also helped me with the mental game.
So bottom line for me, get both. Five years later, I still watch both and when I'm introducing a newbie, I let them borrow both.
P.S. One word of warning...the music sucks on the Kayak Roll. Do not let it get in your head. On my first successful roll I came up doo dooing that stupid song.