Welcome, and best of luck with this. As someone who is not a JW, there is no reason you can't do your own research and present it to him, even if it would be considered "apostate" by JWs. If he tries to use the buzzword, try to explain to him that you are trying to learn both sides of the JW doctrine with an open mind, and whatever label he wants to put on certain reasoning, the most important part is what is correct. I think the books that were mentioned were a good start, but I think specifically what logic you use depends on what kind of person he is and what attracts him to JWs. Some JWs are really into the prophesy and doctrine (and I think a large percentage of those are the ones who end up here, lol). If he is into the detail of bible chronology, prophesy, etc, I think the best ammunition is the sheer frequency with which they change their interpretations of these. It's enough to make your head spin. There is plenty about that here and on the other Truth about JW sites & blogs.
But for a large portion of other JWs, it's enough for them to wave their hands and assume all of the "deeper" doctrine is true, because they enjoy the social aspect of it, or they are under the impression that the JWs are "cleaner", "happier" or whatever, or the glitzy prospect of living forever on earth is too good to pass up (even if it does sound a little too good to be true). It can be a little harder, because this group tends to not care about or even understand the doctrine, so proving its foolishness is not going to help. I think if this is the case, it's a combination between discovering the underlying reason he feels some kind of need, and exposing the cracks in the armor. Things like the families they break up through shunning, the intellecutual growth they stunt by discouraging education, the lives lost due to the blood policy and former policies that have now been tossed away, like vaccines and organ transplants. Not to mention the change in the blood policy where they now take all kinds of things that are part of blood, like hemoglobin, which is almost the entire red blood cell. They love to use the illustration that if you were told to abstain from alcohol, would you inject it in your veins? What about if you had a peanut allergy, would you eat peanut butter, peanut brittle, and things made with peanut oil? Would he want you to be left a widow if he got sick and needed a transfusion because of following this organization's strict, but ever changing blood policy? If they change their policy in 5 years like they have done lots of times before, will he have died for God or died for his Watchtower leaders?