Very interesting (you must either have a photographic memory or you took a tape-recorder to breakfast with your buddy.)
I can understand JW's objections when they say "but who else can I go to". It's easy for us to fliply say, "Why Jesus of course. You don't need an Org". The problem with that is that there was an organization of congregations in the 1st century. People didn't just sit at home alone and read the bible on their own in the 1st century Christian arrangement....they congregated together and preached to others. Association with other Christians is clearly set out in scripture. It's very hard to totally shake this reasoning in the JW mind.
A better tack to take is to admit that some sort of organisation is logical for Christians and scripturally supported, but JW's cannot presently be the organization that God is using for other reasons, like you already touched on, eg, it is easily proved in their own publications that they set them themselves up as a prophet-class, a Jeremiah Class, a John Class, hence they are indeed modern-day prophets whether they like to admit it or not. And as the evidence clearly shows they have made false predictions in Jehovah's name. Also, Jesus said that by their fruits you will recognize them. The paedophilia, NGO association, harsh judgementalism and conduct at congregation level, mental problems, broken marriages and families, shunning, high suicide rates etc, lack of genuine love for non-jw's people except for starting bible studies, etc, etc, all show that the organization is producing rotten fruitage.
Using these tactics to counter-act JW think can help a JW see that his religion simply cannot be the one true religion. To reinforce this you can suggest that perhaps Jehovah will create such an organization in the future that he will draw people to, but presently JW's simply cannot be that one true religion. Why not? Because they fail to meet the bible's own criteria, of producing good fruits, having true love, and not making false prophetic utterances. Point out Having some 'accurate knowledge' is not enough, because without love and good fruits etc the org is nothing more than a 'clashing cymbal'.
So the JW can thus be helped to see that something is very faulty with the notion that there religion is the only true one that God is using today, using the bible's own criteria. Yet they can be helped to come to understand this epiphany without us having to attack the idea that an organization is not required at all, because the bible does not support that notion.