Here's the advice I usually give: Do you need to use packages that only support Python 2 and there are no alternatives? Use Python 2. Otherwise? Use Python 3.

Here's the advice I usually give: Do you need to use packages that only support Python 2 and there are no alternatives? Use Python 2. Otherwise? Use Python 3. If someone doesn't know whether they should be using 2 or 3, they should be using 3.