Plagiarizing myself from another thread:
On a decent screen with font anti-aliasing (“ClearType”) switched on, the right kind of serif font should look more legible for most people. Still, serif or not, the font you see on Forumosa now is the one you yourself selected in your browser, and the same one you’ll see on many other websites, for example on Wikipedia. Good web design is about respecting those settings and Wikipedia’s layout, which also follows this principle, withstood the test of time quite well.
For many people who have never touched this setting, the default font might be something like Times New Roman, which is admittedly ugly, but the good news is you can change it anytime. Personally I use Caecilia, which comes with Amazon Kindle. Other very legible serif fonts that can be downloaded for free include Charis SIL, Sanchez Regular, and Amasis. Even if you don’t want to install any new fonts, you most likely already have Microsoft’s [Georgia] (https://en.wikipedia.org/wiki/Georgia_(typeface)) or Cambria, which you can try.
Of course, if you really despise serif fonts, just choose a sans-serif one (try Segoe UI or Calibri) but the point is, with the things the way they are now, the font you see on Forumosa is your own preferred font from the browser’s settings, so if you don’t like it, just go there and change it once and for all. I certainly appreciate the ability to do just that. Thank you @tempogain, @GooseEgg for all the hard work!
Incidentally, phpBB also respected the user’s preference and did not impose Arial upon everyone, although it defaulted to the sans-serif font.