Join them both. NRA does good hunter/shooter safety programs and serves as a lightning rod for the wrath of the antis. They have the most clout and access in Washington. GOA and the other, smaller groups serve as the REAL gun lobby; I rely on the GOA grading of politicians not the NRA's. What we need to do is take back the NRA from the compromisers, explain that compromise has gotton us nowhere and will be our downfall. Let's get inside the NRA and put some steel in their spine!
JPFO puts out some great literature and pro-freedom propaganda to counter the junk from the touchy-feely Brady crowd. You know, I think SAF does a lot of good behind the scenes work too, but it's mostly research.
Pink pistols? Want to freak your enemies out, join these guys! Groups like pink pistols are the wave of the future, if you ask me. If the RKBA movement is to survive it has to adapt to new political realities. The reality is that gays are politically powerful, especially in liberal districts. That politician who throws away the NRA's postcard will listen more closely to a letter from a member of his traditional voting constituency.
In social movements there are always more hard-core splinter groups that break off from the mainsream. The bigger the group, the more diverse its members, and therefore the more moderate it is. I think most of these groups are good people.