Let's try to boil this all down to a few, basic concepts. The highlights of the information presented above are:
You can't make really bad fonts look nice. TrueType (and secondly Type1) fonts are what you want (for GUI applications) where scalable fonts are required. Further, life will be easier if you install at a minimum the so-called Microsoft core web fonts. You don't need zillions of fonts for every day usage. A nice handful of the basic ones works wonders. This is probably the single most important step.
Fonts won't look good with poor monitor settings either. Make sure your monitor settings are optimally configured, and the dpi is correct. XFree86 v4.x seems to generally do a better job with this out of the box than earlier versions, but if you have butt ugly fonts, it is something you should look into.
Make sure your preferred fonts come first in the font path. X will often have more than one choice available to meet an application's criteria, and whoever is first in the fontpath will win out. The fontpath can be set either directly in XF86Config or the font server's configuration file (if a separate font server is being used), depending on your system is set up.
If using XFree86 v4.x, make sure that the appropriate Xft configuration knows where your preferred fonts are.
And then tell your applications which fonts to use. Don't assume they will make intelligent choices about fonts you add to the system. The defaults may be safe, but boring.
That covers the big items. If your fonts still look "ugly" after going through the above steps, don't expect the fine tuning with additional configuration, like anti-aliasing, to make major differences. Improvements, yes, but taking butt ugly and making it not so butt ugly, then no, not likely.