To be strong, a brand ought to be creative, be properly used, and be registered with the USPTO.
A creative brand name that is unregistered is difficult enforce as it doesn’t have the benefits and strengths that generally accompany a USPTO registration. It will thus be lacking the strength it could and should have if registered.
A creative brand name that is registered but not used properly with the ® and to stand out as a brand is lacking brand awareness among its users and consumers. It will lack strength as a result.
A brand that is registered and properly used, but that is not creative will not stand out in its industry. As a result it will lack strength and distinction.
See visual below for more details.
For more of my trademark visuals, see https://www.erikpelton.com/resources/trademark-visuals/