Arkenfox is great, although worth noting that there are always privacy vs. security vs. usability tradeoffs. The best usability settings (in terms of sites just working at least) are generally the Firefox default and Arkenfox defaults aims for privacy mostly but they also have some of the best descriptions of available configuration available anywhere (often the only other source of any kind of information is a brief comment in the source code that assumes familiarity with Firefox code). Personally, I aim for the best security and accept that that makes me unique.