The KJV Only argument is one of Satan's most divisive tricks. For people that speak only one language, most of the world, it is impossible to understand the trouble with translations and when one adds narrow minded bigotry into the mix, a real mess is the result and none to very little will have to do with God. Over the years I've owned 18 or 19 different versions of the scriptures and the amazing thing is that when they are carefully and thoughtfully examined, they all say the same thing in the end.
In my case, the most argued point by the KJV Only crowd is inspiration of the Original Text and when this is considered, intellectually, their basis for argument is the very point of their downfall. The KJV is not an original text, it is translated from, arguably, the original texts, just as are the ASV and the NASB.
My personal preference is the NASB because it is the closest to a word for word translation one can purchase, here, in English. Let me blow a small amount of honesty about here for a moment. When I was in Germany, excuse my German spelling, if a man asked me, "Vos est los," "What is happening," I would have answered, "Der hundt est los." Litteraly I told him the dog is happening but translated, thought for thought, I told him nothing is happening.
So it is that there are two major schools of thought on translating the scriptures, first is the thought for thought method (KJV and many others) and the second is the word for word method as is used in the NASB. Anyone that knows languages can tell you I just lied and I can not argue with them over it. Just as I demonstrated with the answer to Vos est los, it is impossible to do a word for word translation and that is why when we look at the matter it is best seen on some sort of a graphic. When viewed on a lateral graph with absolute word for word on one end and absolute thought for thought on the other end the NASB is just short of being completely word for word as is the KJV just short of being a compete thought for thought version.
I have two printings of the KJV and four printings of the NASB and they are not the limit of the versions I use to teach from. The biggest problem with any version only church is their focus. They are not focused, completely, on the mission Jesus appointed to them in the Great Commission.