Both have their pluses and minuses. Najdorf has a ton of theory to learn. You have to be prepared against 6. Bg5, Be3, Be2, h3, and also possibly a little bit of f3 and f4. Najdorf is considered the "best" but you have to take a lot of time to learn it.
Hyper Accelerated Dragon has a lot less theory, but you must be prepared to play against the Maroczy Bind where white plays c4. I personally prefer the Hyper Accelerated Dragon and have had some good wins with it. There are also some ways to fight against the Maroczy Bind, so you have to decide which kinds of positions you like better.
Hope this helps you!
hypostarts e4 c5 nf3 g6