Every US Gun Owner Should Support the NRA
People can quibble with some of the NRA's moves over the years - there are some legitimate goofs to criticize. And there are a few gun rights organizations out there that are more "ideologically pure" or more "hard line" than the NRA.
But, over the past 50+ years, no organization has done as much for gun owner rights in the US than the NRA. It is the biggest, strongest, most effective gun rights organization out there. The gun-ban goofballs are constantly complaining about the power and influence of the NRA, and for good reason.
The NRA also sets standards, sponsors competitions, and certifies instructors and classes, and has hundreds of other programs/activities that are invaluable for gun owners.
My take: every US gun owner should support the NRA.
If there is another organization out there that serves some niche interest of yours, or has a stronger position that you like better than the NRA, then by all means support them too.
But whatever you do, do support the NRA.