Since I am not a "KJV-legalist" it would not be fair for me to give their arguments since I might misconstrue something.
Instead I will tell you my stance on the subject. I hold to the KJV because I believe it is a faithful translation of the traditional Greek text as used throughout the Church's history. The Textus Receptus is the Greek text of the Reformation. It, in turn, was made in reliance upon the Byzantine Text readings (this may be an oversimplification, but what they hey, we're a message board not a theological journal) which were the majority text in the ancient churches.
I don't like Westcott and Hort based texts because it seems to me that in holding to them you would have to have a position that essentially says that God's word was lost to the church for at least 250-300 years and most likely lost for as long as 1,000 years. Westcott and Hort based their Greek text upon the Codices Sinaiticus and Vaticanus. These two texts came out of Alexandria and are notoriously untrustworthy.
I also don't trust the newer Greek text because of the people who made it. Westcott and Hort said that they were setting out to dethrone the TR. Therefore they rejected it, and most Byzantine readings, out of hand when they created their text.
I can go on, but this is probably enough to give you the gist of my position.
Have a great night, and I pray that Church goes well for you tomorrow.