cronjecj: This has to do with the translation of the word μονογενες (monogenes), which is a compound of μονος which means "only" and γενος, which means "race, species, kind and family". The reason people like you and I have a problem with this because using monogenes as only begotten, shows the divinity in which Jesus shared with the Father. Saying He was the only-begotten son shows they share a genus, the way a biological son would share with a biological father. They have the same "divine trait" if you will. So people tend to think that the ESV is a horrible translation. Now, don't get me wrong, I agree that it should be only begotten, but the reason the translators didn't use "only-begotten" and opted for "only" is because of the word γενος(genos). Their question was "does it mean family, which would make it only-begotten, or does it mean kind, which would make Jesus one of a kind(or only-kind)?" Hence being the "only" son. I tend to believe BOTH are true. Jesus was one of a kind, AND the only begotten son.
Now, like you, I believe it would have been better to use "only-begotten", but does that mean I think it's a horrible translation, or not the scripture? By no means. Sure, the ESV has it's flaws, and some of those are present in the fact that they were trying to be literal, but the KJV has it's major flaws as well.