Are there nice witches

First and foremost, all witches are people.

All people are a combination of good and bad. There are many examples of both throughout society and history.

Therefore, it can be extrapolated that all witches are good and bad. Even the very best people on the planet have a little bit of bad in them, and even the very worst people have a bit of good in them. No one is all one or the other.

The qualifier here, is that most of those people now practicing one of the earth-based spiritual paths and calling themselves witches are basically ethical people.
In most cases they believe strongly in taking responsibility for their actions, and work with the Rule of Three as a principle guiding factor.
This does not mean that they are perfect (no one is), everyone makes mistakes, but they are conscientious about how they behave, not just with those they know, but also with everyone and everything on the planet.