Which is the best English Bible version?

Simple answer: it depends on what you want to use it for.

If you are reading history, poetry or illustrative stories like parables then use a free-flowing translation or a paraphrase.
There are many of these available as most Bibles in our bookstores are of this type.
Popular "easy-read" versions include translations like
    New International Version (NIV),
    Contemporary English Version (CEV),
    Good News Translation (GNT), and
    The New Living Bible (NLB);
and paraphrases like
    The New Testament in Modern English (PHILLIPS),
    The Living Bible (TLB), and
    The Message (TM).

A common difficulty with these non-literal translations of the New Testament is they usually translate the Greek words that end up as "eternity" or "eternal" or "hell" in the English text quite wrongly, which helps to conceal God's ultimate purpose for His creation. You can read more on this issue by searching previous posts on the BLOG.

So, if you are wanting to form Bible-based opinions about God, His character, His purposes and His plans to achieve them, you will need to search out a more literal translation which does not insert the translator's theology (personal views) into the text.
Literal translations include
    Young's Literal Translation (YLT),
    Concordant Literal Version (CLV), and
    David Bentley Hart's New Testament: A Translation (DBH).

I don't mind if a literal translation provides personal views as comments below the text or in a sidebar beside the text provided that the text itself remains free of such inclusions.
I also don't mind if the text includes a word or two that is not in the original in order to help the readability of the resulting English provided the extra words are designated in some way to show they are additional to the literal text.  Using italics or a different text font are common ways of doing this.

There are also other popular Bibles which claim to be "easy-read" or literal translations or both easy reading and literal.
Bibles like
    King James Version (KJV),
    New King James Version (NKJV),
    New Revised Standard Version (NRSV),
    English Standard Version (ESV),
    Holman Christian Standard Bible (HCSB), and
    New American Standard Bible (NASB).

My research suggests that none of these are literal consistently and only some people might find them to be easy reading.

A warning: I have found some Bibles to be downright deceitful in two subtle ways.
Firstly, Bibles which might claim to be accurate translations and promise to place additional words in italics to show they are not words in the original Greek text sometimes insert extra words which accommodate their personal views without placing them in italics.

Here's an example from The Passion Translation (TPT).

When the non-Jewish people in the crowd heard these words, they were thrilled and they honored the word of the Lord. All who believed that they were destined to experience eternal life received the message.
(Acts 13 : 48 TPT without the italics it promised to include for additions words)

Now compare it with Young's Literal Translation (YLT).

And the nations hearing were glad, and were glorifying the word of the Lord, and did believe -- as many as were appointed to life age-during;
(Acts 13 : 48 YLT)

God's appointment in YLT has been replaced by man's choice in TPT by using additional words without the promised warning.
(By the way, notice the incorrect translation that produced "eternal".)

Secondly, some Bibles might have the words correctly translated, but change their order to accommodate the translator's theology.
Here's The Passion Translation (TPT) again.

Even as all who are in Adam die, so also all who are in Christ will be made alive. (1 Corinthians 15 : 22 TPT)

Compare with Young's Literal Translation.

for even as in Adam all die, so also in the Christ all shall be made alive, (1 Corinthians 15 : 22 YLT)

Once again the TPT has added words without designating them as being added and, together with changing the order of the remaining correctly translated words, has totally changed the structure and therefore the meaning of the verse to accommodate their doctrine that only Christians will be made alive.

The TPT translation has now made this verse conflict with so many other verses, for example:

For he must reign until he has put all his enemies under his feet. The last enemy to be destroyed is death.
(1 Corinthians 15 : 25 - 26 NIV)
This plan, which God will complete when the time is right, is to bring all creation together, everything in heaven and on earth, with Christ as head.
(Ephesians 1 : 10 GNT)
For God was pleased to have all his fullness dwell in him (Jesus), and through him to reconcile to himself all things, whether things on earth or things in heaven, by making peace through his blood, shed on the cross.
(Colossians 1 : 19 - 20 NIV)

So which is the best Bible version for you?
I suggest you start out with an easy-read translation or paraphrase for engaging with the story-line, but then use a literal translation to check the accuracy of what you have read and to filter out the theology of the translator(s) if you are building a Biblical point of view on a particular subject or issue.

Blessings, Barry