In my opinion, Google is the worst. 

A colleague at the hotel utilized Google to translate a guest comment  from Spanish to English, the translation was so bad and grammatically it was all wrong.  I had to translate again and ended up doing double work.

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I suppose it depends on what you are translating. Google Translate seems to be sufficient for translating simple words and simple sentences (like phrases one would need while traveling), but the more complex the passage is, the more diluted it becomes during the automatic translation process.

I also agree that Google Translate has improved in recent years, but maybe that's because I speak English. There is always someone who wants to translate something from their native language into English. Even so, I know it's still not always perfect. I cannot speak for the accuracy of automatic translation between, say, Icelandic and Mongolian.