I grew up going to traditional Baptist churches, so I grew up on the KJV. But I found the old English to be hard to understand. I prefer the New King James because it is the KJV I've become used to, but with modern English to make is easier to read and understand. To me the NKJV is like the bridge between KJV and NIV. Sometimes when studying verses, I like to read the KJV version, then the NIV, then the KJV again, then it makes more sense to me.
What I can't understand are legalists who think that the KJV is the ONLY good bible and all others are "evil" (especially the NIV). Sadly, I've dealt with that a lot in the Baptist churches I've attended growing up (which is one of the reasons why I'm glad my wife and I now attend a non-denominational church). Yes, I agree the KJV is a good translation, but the problem with thinking it's the "only good bible" is that the KJV is NOT the original inspired word of God. It's a TRANSLATION of the original inspired word of God. So obviously it can't be the ONLY good version of the Bible. It just doesn't make sense (along with many other rules and regulations that legalists have created).