brent There's a correlation between, privacy, compatibility and ease of use.
The choice to not delete Cookies and Site Data each time you close the browser, improve privacy a very tiny bit, but absolutly butcher the ease of use and perhaps a bit of the compatibility.
Firefox already isolate your cookies and site data per website. So, you are just deleting your cookies exclusive to that website everytime. Asking the regular user to whitelist EVERY website they want to conserve data is absolutly not intuitive.
The secure DNS setting is just the usual Firefox option, to prevent issues with compatibility while normally, not worsening Privacy that much.
There's just no "perfect browser" for everyone. As you can't maximise all of those three points ideally.
If you maximise Privacy, you tend to break compatibility and ease of use.
If you maximise Compatibility, you tend to weaken Privacy and ease of use.
If you maximise the ease of use, you weaken the user privacy by assuming their choice, and consolitate compatibility.
Example :
If you want a truly private browser : Go for the Tor Browser, however, it will break the compatibility of tons of newer web features, and break the ease of use for the normal user, by deleting their data everytime and having to deal with constant Tor network blockage and some shenanigans compared to the average user web usage.
If you want a truly compatible browser : Go for the Google Chrome browser, however, it will obliterate your rights to privacy compared to other options by default, and will assume plenty of features for you, like DRM, WPA's, and password saving.
If you want a truly easy to use browser, Go for Epiphany/Falkon or plenty of others recommended there, but they will not be as compatible as others and will not be able to be private as others due to simplying the settings a lot, compared to what you could tweak it.
My sayings and points are a tad flawed (perhaps from trying to over-simplify it) and need to be rewritten, but for short :
tl;dr :
Privacy
/\
/Ⓣ\ Ⓣ Tor Browser
/ \ â’¼ Ghostery Browser
/ \ â’º Epiphany/Falkon/Midori/Safari
/ \ â’¸ Google Chrome
/ \
/ â’¼ \
/ â’º \
/ \
/ â’¸\
--------------------
Ease of use Compatibility
Ergonomy