I just moved back to openSUSE after spending almost 2 years in ubuntu-land.
What happent to the fonts? Why are they so ugly? To me it looks like they are poorly rendered.
I installed openSUSE 11.2 on another computer to confirm the problem… it persists.
I rarely use Firefox; so I am not sure how you might address this but I have noticed that in some applications the quality of a font improves with a change in magnification. Does zooming improve the quality?
It is possible that, though the fonts look the same size in Ubuntu and openSUSE, there is a slight difference in magnification at a crucial size for openSUSE.
I use Firefox, but have not really noticed a problem. (I can only compare openSUSE against Windows with Firefox and OpenOffice, and the latter is supperior). However I found this web page which suggests
The subpixel hinting implementation in freetype2 is disabled both upstream (by the freetype2 authors) and in the freetype2 RPM packages that ship with openSUSE because it might infringe Microsoft’s ClearType patents.
and explains how to rectify this by installing another package version.
Now, the author mentions that this is for improving fonts within the KDE environment, and they also have a suggestion for GTK apps within KDE, but it might help you pinpoint any differences that Ubuntu has with font rendering.