The answer to the question is fairly simple
The JW's have gradually fixed the truly problematic renderings, (Like John 17:3 for example.)
Most of the rest of the criticism is driven by doctrine and is therefore debatable.
Yeah, the NWT is definitely biased, but that's not unusual as Bibles go.
The NIV leans strongly towards American fundamentalist, trinitarianism and the NAB (In editions prior to 1970) leans heavily towards an orthodox Catholic male-centric viewpoint.
Religious people have a habit of translating in a manner most favorable to their own teachings and that's just human nature.
Yeah, the NWT has some quirky renderings, but they still fall within accepted boundaries of grammar and definition. They may not actually capture the "spirit" of what the writer was trying to say (Whatever that was) but that's a subjective argument that invariably carries a boatload of preconceived ideas about the Bible itself.
Nothing screams "I can't actually read the source language myself" louder than saying the NWT is full of "made up crap" (No disrespect to the late oompa intended)
It's on par with adolescent American males arguing over the meaning of Rammstein lyrics. (Wenn man auf Englisch darüber streiten, sollten sie überhaupt nicht streiten.)