The best reply to the statment that JWs don't claim to be 'inspired prophets' is to point out to them that you don't have to claim to be inspired to be a false prophet. What false prophet was ever inspired anyway?
It's a bit of a play on words but it works very well.
On the point of the apostles having wrong ideas, there is no biblical proof that they shared their wrong ideas in their ministry, unlike JWs.
The other point to bring out is that Jesus corrected the wrong ideas of the apostles right away. He didn't leave them to promote their wrong ideas for 70 years or more, excusing such errors to the fact they were imperfect men. If Jesus is directing them now, why is he not continuing to correct his followers like he did in Acts 1:6
Both of these points contrast the truely appointed from the self appointed. The fact is that JWs are false prophets even by their own definition and standards.