The KJV has value not only because of the set of manuscripts in the original languages that was used but also because of the faithfulness and heart attitudes of the translators.
The best evidence is that the translators of the KJV consulted not only the original language text but also the earlier English translations such as the Tyndale, Coverdale and Geneva Bibles and re-used significant portions of these earlier works. IMHO, the translators did not needlessly make changes to translations that others had already studied and memorized.
Many modern translations commonly have deficiencies that include:
* Making a translation vague where it could have been much more concrete and specific.
* Generalizing the vocabulary (also known as "dumbing down") and combining multiple words in the original language into one word in English.
* Changing word order around from the word order in the original to make things less clear.
* Interpreting the original and making assumptions that are presented that rather than translating more closely to the original.
* Skipping words, changing words, adding words in the English translation to make the translation to be different in English than it was in the original.
* Taking strong, serious statements and statements well positioned to influence a response and making them less likely to offend and less likely to influence a response.
As mentioned, these issues are unrelated to the original manuscript and are more related to the heart actions of the translators.
Other translations can be better than the KJV for particular verses but the KJV remains the most serious, sensible and reliable overall.
The KJV also benefits from the hundreds of years of sermons and books and Bible study tools that have been developed in coordination with the KJV.
Strong's Concordance tools, originated in the nineteenth century, are very helpful for mapping between words in the original languages and their equivalent in the KJV. The Strong's Concordance tools are usable by nearly anyone. Other tools like a Thayer's Greek lexicon and Hebrew / Greek concordances have been tied to the Strong's Concordance and the KJV.
For computer tools, the web site at: http://www.scripture4all.org/ provides the Interlinear Scripture Analyzer (ISA). This is a free interlinear Bible software tied to the Strong's Concordance and KJV. This tool is not from my denomination but it remains very helpful and I use it often. With this tool, you can see the original language text and the associated Strongs Concordance word and KJV word.
The Blueletter Bible web site at http://www.blueletterbible.org is an online tool that I use often for general lookups and for comparing modern English translations. Its default English translation is the KJV.
Use the tools above to compare the original to the KJV and to compare modern translations to the KJV. You will see differences but also get insight.
Another benefit of the KJV is that is available in the public domain and is free to use without the need for citations with attribution to publishers and copyright holders.
The stability of the KJV for over 400 years now has helped to maintain the stability of the English language which sometimes acquires new words and expressions.
For those who know spoken and written languages other than English, I recommend that they use translations better fitted to those other languages than the KJV.
When I began to read the KJV during high school (I grew up as a Roman Catholic), it seemed nearly unreadable but I was mentored to use it and it became easier to read and use.