Many will not accept anything other than the KJV...though I would ask which one (1611 or 1769)? William Tyndale completed the first English translation of the NT using Greek manuscripts and the Pentateuch in 1530. King Henry VIII did not approve of Tyndale's Bible translation so he commissioned what became known as the Great Bible which incorporated much of Tyndale's work with a gentleman named Myles Coverdale translating the missing books using primarily the Latin Vulgate (which included the Apocrypha) and some German texts.
The second authorized English translation is known as the Bishops Bible in 1568. This Bible underwent substantial revision in 1572 and became the basis for the 1611 Authorized King James Version. By the 18th century, there were so many misprints in circulation that the Universities of Oxford and Cambridge undertook a substantial revision with the goal of a standardized text. The Oxford version became the dominate version published in1769. It is this 1769 Oxford translation that most of us own today.
The New King James Version is certainly not without critics but it largely uses the same Greek, Hebrew, and Aramaic manuscripts as the 1611 KJV. The decision to use those textual sources excludes discoveries that have been made since the 1611 translation was completed. Still, the decision to limit the source material to the same manuscripts as the 1611 KJV is interesting and deserving of discussion.
Contemporary scholars have taken advantage of the additional manuscript discoveries that were unavailable to Tyndale and those who followed him. In my personal and seminary studies, I use a number of translations. I have also become a fan of word studies. Computer software allows us to dig into the original languages and see how various versions translate a particular word. I do this to gain a fuller understanding than that allowed from any single translation. Scholars can and often do disagree on things. Biblical translation is no exception.
Despite what some may believe, the original Biblical documents have not survived from antiquity to today. Even 500 years ago, scholars worked from copies of copies. Fortunately for us, there are over 5000 manuscripts and fragments of manuscripts available today (far more than all other ancient writings combined!) that we can compare. The texts are incredibly consistent!
While there are some highly questionable translations on the market today, we can certainly be confident the the KJV and NKJV are both faithful translations of the surviving manuscripts. I also use the ESV and NASB often in my study. While the 1769 Oxford KJV is my preferred Bible, I own and use other translations and have been edified from their use.
The best thing I ever did for my Bible study was purchase a wonderful software package that allows me to accomplish so much in a very short period of time.