There's one or two more things I can think of that haven't been mentioned, and that's:
-- your DPI setting (dots per inch), which does affect how your fonts look.
-- your anti-alias setting(s), which relate to both the subpixel layout of your monitor, and the level of anti-aliasing (smoothing) that is done to the fonts.
Both these items can have a significant impact on the look of your fonts, and on your eye comfort when viewing your monitor.
Right off top of my head, I can't remember a good one-stop location to read all about these, but as one example of how to set this stuff up, here's what I use in my ~/.Xresources file to configure how libXft affects fonts:
shell$ cat .Xresources
! libXft settings !
Something tells me there's somewhere else on my system, where I set something to do with the DPI setting, but again, I can't recall exactly what or where - but if I do, I'll post again any info I find.
Meanwhile, I recommend Googling for .Xdefaults, .Xresources, libXft settings, and antialiasing, and see what you come up with.
Also, for your "rgba" setting, which is based on the subpixel layout of the pixels in your monitor, check this site to read about this and find out which arrangement you have: http://www.lagom.nl/lcd-test/subpixel.php
And here's a "ScreenFontSettings" X11 page at freedesktop.org, where there might be some more info: