Is ghostery safe to use?

The answer to your question - Is ghostery safe is that you can prevent Ghostery from selling your data by opting out of the Ghost Rank feature. The feature is opt-in, so if you didn't already opt in there is nothing you need to do. It is then safe for you to use. Using a clone of Ghostery which is identical in every aspect except not having the Ghost Rank feature would make no practical difference from running Ghostery without opting in to Ghost Rank. If your intention is to actively punish Ghostery for their evil data trading by boycotting them, then you will achieve nothing. They already gain nothing from you commercially when you run Ghostery with Ghost Rank disabled. If anything you help them by uninstalling Ghostery because you no longer consume any of their resources. 

But if you are really looking for an alternative option: the classical method is to edit your operating system's hosts file and forward the hostnames of known trackers and advertising networks to 0.0.0.0. There are recommended blocklists available which you can find with a websearch (I can't vouch for their quality, so I won't recommend any specific ones). The advantage is that it doesn't just block advertisements in one web browser, but in all web browsers you have installed and in any other applications which might access these hosts for whatever reason. The drawback is that you will have to maintain your blocklist manually.