Another argument I have used lately with my family is that even if the WT was correct on every doctrinal point (which obviously they are not) the biggest thing that drove me away was the lack of true compassion and "Christian" love from the majority of the congregation, especially the elders.
I have been bringing up doctrinal points in small doses, but the biggest scriptures I use against them is John 13:35 (my disciples if you have love among yourselves) and 1 Corinthians 13 (pauls description of love).
I love the irony, since the WT uses John 13:35 to "show" they are a true brotherhood, and they are using 1 Cor 13 (love never fails) as their year text! The WT's version of love makes me want to vomit. LOVE = TOTAL OBEDIENCE (Sounds like I LOVE BIG BROTHER)
I like how Ray Franz described it in his book - the WT produces people with generally good morals and an outward appearance of warmth, but underneath they typically lack compassion toward others. Obviously that is a general observation since I truly do know JW's who are wonderful people (and I hope I was one when I was in there) but I think it is especially evident among elders - the WT produces more men who are judge, jury, and executioner than kind, warm, compassionate shepherds.