I have my own differences with the NRA, but they are the biggest gorilla on the gun rights block, and they are usually very effective, so I maintain my membership.
I am a life member, but the NRA does offer a $10/yr “Associate” membership for those who may want to join but perhaps want to put more efforts into other gun rights groups. However, the NRA is definitely the biggest gorilla on the gun rights block as you say. Associate members will not receive the magazine choices from the NRA.