Pale Moon is the best one I have found.
I've been using it since you told about it the first time. As of lately I've noticed two things which I'd like to be explained.
The first one is obviously a bug: PaleMoon lost a great deal of my saved login information. Yes, I know, but the saved ones pose no actual risk. Well, maybe if someone stole them, said someone could impersonate me here. Anyway I could easily get them back from Firefox.
The other one is about my bank saying my browser is not supported, giving a list of supported ones. Now my question is, whether this could only be lack of knowledge by their side or could there be a flaw which could reduce safety? Just for the record to you on the other shore of the pond, we don't actually need dedicated banking browsers due to a more complicated identification system our banks use.
Other than those I've been very happy with PaleMoon. Every incompatibility issue so far has been due to NoScript...