Fortunately, there is help available in evaluating the many different English language Qur'ans sitting on bookshelves today. Khaleel Mohammed, who teaches in the Department of Religious Studies at San Diego State Univesity, wrote an article for the Middle East Quarterly in which he said of various English translations:
"Some are simply poor translations. Others adopt sectarian biases, and those that are funded by Saudi Arabia often insert political annotation. Since translators seek to convey not only text but also meaning, many rely on the interpretation (tafsir) of medieval scholars in order to conform to an "orthodox" reading.
Khaleel Mohammed offers brief comments on twelve English translations. For most academics, he says, the translation of choice is that of Arthur Arberry: The Koran Interpreted: A Translation.
The translation is without prejudice and is probably the best around. The Arberry version has earned the admiration of intellectuals worldwide, and having been reprinted several times, remains the reference of choice for most academics. It seems destined to maintain that position for the foreseeable future.
His comments on many available English translations of the Qur'an makes this article well worth reading.