A handful of things come to mind if I was cornered. I've already used a few and watched some family members squirm.
I'd say, "the faithful & discreet slave" being something prophetic as opposed to being simply a parable for illustrative purposes. I don't think you'll find one JW capable of making a reasonable argument that it's prophetic and the WT is the only logical conclusive group that it exclusively applies to. Their own literature on the subject, such as the Insight Book, doesn't even make a solid case. It briefly touches on what other faiths believe it to mean, but doesn't bother to make a sound argument against what those other belief systems present. Another facet of the WT's view on the parable in question is their constant reminder to JWs in the literature that what they're reading is from the faithful & discreet slave and that we should be submissive and yielding to their word. Meanwhile they'll also remind you occasionally that they're not infallible, yet through the COs and Elder bodies, anyone who questions their word will find out otherwise.
Another one that bugs me is the assertion that only active JWs will survive the Great Tribulation leading into Armageddon. That flies in the face of Scriptures such as Matt 7:1, and even more so in the face of Mark 9:38-40 which is barely ever mentioned in any of their literature. It wouldn't surprise me if they omit those verses in Mark entirely somewhere in the near future or edit them so that the brevity and weight of those words are lost on the average JW.
Field Service being mandatory for everybody is something that bugs me as of late too, mainly because I hate doing it anymore. Eph 4:11 speaks about the Lord giving to His flock different roles for different indivuals that would benefit the congregation as a whole. He specifically stated that some would be prophets, some evangelists, some teachers, etc.. It didn't say everyone would be an evangelist, so why the peer pressure upon people aren't either naturally inclined to preach, or don't have the ability to do such? To illustrate the lunacy of it all, why can't all be prophets since all have to be evangelizers?
Aother thing that bugs me, and bugs more than a few JWs I know personally who will express the same sentiments behind closed doors, is the stance towards higher education. The WT's stance on this is not Scriptural, but then again something not being in the Scriptures hasn't ever stopped them before. They take the thoughts expressed in the Bible about not being part of the world, or not using the world to the full, and verses condemning greed as being applicable towards anyone going to college. I don't anyone who went to college because "they wanted to make a lot of money."
The last thing that bothers me is the blood doctrine. We're reminded occasionally that we're not under the Mosaic Law, although the basic principles found within it are set in stone. So the mention of abstaining from blood in Acts serves as an extention to what's in Leveticus. My thing is, if everything is so black and white in WT land, why can't they be consistent on blood in regards to blood fractions? Under the Mosaic Law, the blood was to be DISCARDED ENTIRELY. There was no room for processing the blood into fractions for further use even if they had the ability to do such a thing back then. So in Acts, Paul brings it up that these new Gentile Christians are supposed to abstain from blood which is an extention of what was found in the Law. Paul didn't say to break the blood down into fractions and then it's acceptable. No, he said to abstain from blood, and in order to figure out what he meant according to the WT, one has to go back to what's found within Leveticus. The WT knows they F'd up big time with their blood doctrine, but they're screwed royally because it's been enforced for so long under the threat of sanctions. So they tried to weasle out of it the best they can by ok'ing blood fractions, but if we're going to keep is Scriptural according to WT definitions, then blood fractions are not acceptable. Not blood is acceptable, none of it.
