I think the Apple Store could be better for you mainly because you can get some rapid, one-on-one assistance on not only your Apple ID problem but some assistance with other setup items and quick instruction. Walk in the store, say you need help and they will give you an appointment with one of the Genius folks there. If you're interested, you can also sign up for an orientation session to later go into more detail on how to more fully operate the IPhone. Appointments with the Genius person generally take a 15 minute to 2 hour wait. Best time for a short wait is to avoid weekends.
Last, you can get excellent assistance with any IPhone (or any other product) even if it was not purchased directly from Apple. For example, my IPhone was through AT&T and I have solely used an Apple store for any and all help through the years. Good folks.
