We have two problems as gun owners that national RKBA organizations work to address, cultural and legislative. Some organizations work on promoting the shooting sports while others concentrate on legislation that impacts gun owners.
The NRA does both with a variety of support for shooting programs and it's legislative work.
What are the pros and cons of the NRA?
As the oldest and most experienced of the shooter's organizations they have a lot of influence the others might not have. They have extensive state organizations that influence politics and politicians at the state level which also translates to influence in Washington. The other organizations just don't have roots that spread that wide or go that deep.
The perceived cons are probably dependent upon what annoys an individual. No one likes getting begging letters or calls asking for money, but I'd rather have an organization funded by a broad base of members than a small group of contributors who can act as an oligarchy within the organization. The antis are funded by a few who want to engineer the many into their image of society. The NRA is at least funded by the members.
What other national RKBA organizations are there?
Most people forget about the
NRA-ILA, but it is a separate lobbying/legislative arm of the NRA. Contributing to it contributes to directly to the court and legislative effort to protect gun owners' rights.
Gun Owners of America (
GOA), is a smaller feistier group that takes a very aggressive position on straight RKBA politics. They don't get as involved in shooter education or hunters' rights as the NRA instead addressing 2A issues only.
Second Amendment Foundation (
SAF) is another 2A only organization that works legislative RKBA issues.
Jews for the Preservation of Firearms Ownership (
JPFO) is another "in your face" 2A organization approaching things from their particular perspective. They do a very good job at making the point that the 2A isn't an out of date concept.
Someone is going to bring up the AHSA (American Hunter's and Shooter's Association) so we might as well toss it on the table. It is an organization claiming to be a viable alternative specifically to the NRA, but somehow supports banning certain types of firearms. The folks that started it come from the anti organizations and their membership is tiny (really tiny) while their visibility is disproportionate to their numbers. They've been discussed repeatedly here and those discussions are easy enough to find.
How do the others compare to the NRA?
Every other organization is smaller than the NRA. That's important in politics because the more members you have and the more money you can dedicate to the cause the more effective you can be nationally. I'd join the NRA and another national organization and work on the local level to protect your rights as a gun owner. Remember that every politician in the state capitol AND Congress is elected by the people of their state.