Jehovah's Witnesses?

Once again, the trinity is denied.  Jesus is not God, but instead they say he is "a god" (small g).

The Bible (and the protestant Christian faith) teaches us that Jesus is equal with the Father, that he and the Father are one.

JWs (Jay Dubs) twist scriptures to suit their perspective rather than informing their perspective by the scriptures.  Be wary of any group that does this, but remember that many who belong to such groups are manipulated to believe for many different reasons.

Here is a heap of resources.

JWs in a nutshell (from www.carm.org)

What about all of the different denominations - how to choose?

This is both hard, and easy.

Hard because there are so many that claim to be Christian.  Easy because when you have a principle to follow there isn't a problem.

Here is/are the principle(s):  Before committing to any group, make sure they believe the Bible, are willing to change when they see their errors, and are not so fast in making decisions that they forget what is important.

With a foundation in the teachings of the Bible, it won't matter what denomination.  All of the core principles of Christianity come from the Bible, so you can be sure you'll be okay in a place where they look to God's Word.

If in doubt, you can search for the denomination name on the cultwatch website to see if they are dodgy.  Another resource of Cults and Religious groups is here.