I didn’t find many comparisons between the two let alone a recent one. So they’re both packages for changing Firefox prefs for better performance and or privacy. I’m interested in applying them to Zen Browser. Can you provide detailed comparisons and if I should you use both?
Both of them are very well documented with sources and explanations in the comments. You could pick and choose what you need and understand to create your own. Speaking from experience, using these prefs without knowing what they do might cause you a headache down the road when something breaks.
Betterfox should be the one with least breakage.