Fonts on Ubuntu - revamped

Some years later, I am at the same spot: trying to get proper font rendering for ubuntu, this time 16.04. After some research, these are my findings:

Ubuntu Tweak is where one can set the fonts for Unity - this affects most menus, and some of the apps
Other apps, especially firefox and thunderbird, don't respect this setting. They respect fontconfig though - so one has to configure both.

fontconfig is configured in /etc/fonts/conf.d, and also in ~/.config/fontconfig/fonts.conf. A good resource to understand this is https://wiki.archlinux.org/index.php/font_configuration
one can check what fontconfig will match for a given font name by: fc-match fontname
Firefox and thunderbird might update their rendering after fontconfig has rescanned the configuration. This might happen, but to be sure, better restart them.
Firefox and thunderbird have font settings for each encoding. So one has to set proper values for 'latin' and 'other writing systems' which is their acronym for utf-8.

I like my fonts to be crisp, like in the screenshots below, and I don't care too much about the actual font shape. I don't use MacOS (or whatever OSX is called these days) :-).

So, In Ubuntu Tweak I selected the following settings:

Before configuring fontconfig one has to understand the problem of Helvetica. Lots of websites want it, but Ubuntu delivers a really unsuitable replacement. Thats why lots of websites look ugly, unless a better alternative is configured. I like to use Arial as a replacement, but DejaVu Sans would do as well.

To get Arial I have to install it. In 16.04 there is a bug though, but loading the upgrade debian package helps:

wget http://ftp.de.debian.org/debian/pool/contrib/m/msttcorefonts/ttf-mscorefonts-installer_3.6_all.deb
sudo dpkg -i ttf-mscorefonts-installer_3.6_all.deb

This leaves my fontconfig file in ~/.config/fontconfig/fonts.conf

<fontconfig>
 <match target="font" >
 <edit name="rgba" mode="assign"><const>none</const></edit> 
 <!-- <edit name="lcdfilter" mode="assign"><const>lcddefault</const></edit> -->
 <edit name="hinting" mode="assign"><bool>true</bool></edit>
 <edit name="antialias" mode="assign"><bool>true</bool></edit>
 <edit name="autohint" mode="assign"><bool>false</bool></edit>
 <edit mode="assign" name="hintstyle"><const>hintfull</const></edit>
 </match>  
 <match target="pattern">
 <test qual="any" name="family"><string>Helvetica</string></test>
 <edit name="family" mode="assign" binding="same"><string>Arial</string></edit>
 </match>
 <!-- <rescan><int>5</int></rescan> -->
</fontconfig>

In Firefox I have the following font settings (remember: latin and other writing systems):

Update: I use 16 now instead of 14.

In thunderbird (latin and other writing systems):

Last there are the qt based apps. like skype, where the font is a bit to small for me. So I used qtconfig from qt4-qtconfig, changed appearance to another style, saved, changed back to Desktop Settings (Default), saved again. and now it looks good.

Last note: I tried using Helvetica and Helvetica Neue from MacOS, but they don't render nicely with hinting set to 'full'. If hinting is set to 'slight', using the MacOS creates a nice visual experience (but as I said, I need crisp fonts)