If you have any concern for individual liberties, you should join the NRA.
I have no idea how any gun owner could be so upset with the NRA that they refuse to support them. The NRA has never been perfect, but for many years they were the only barrier between America and total loss of gun rights. If we lose gun rights, all other rights will follow.
There are other groups that have also done great work over the last few decades, like SAF, GOA, CCRKBA, Firearms Coalition, and more recently JPFO has answered the call. You should support as many of these as you can, and also join your state level equivalent(s) to the NRA.
My personal observation is that some people are too cheap to pay $35 a year to join (you can often find discounted memberships at $25) and then rationalize their cheapness with a bunch of psychobabble. These folks are of no value to the rest of us.
We have to accept the fact that individual liberties are being constantly eroded, and we need to support organized efforts to slow or reverse that erosion, even if the organizations are flawed in some way. Any large organization is going to have flaws.
The only people who have a right to criticize the NRA are voting members, or people who support other similar organizations. If you donate significant time and money to GOA, SAF, CCRKBA, etc, then you have some call to criticize the NRA, although I bet at that point you would understand how badmouthing the NRA could never help gun rights to move forward.