Ugh, the anti-aliasing kills most of them for me. I realize I'm probably in the minority, and my opinion might change as screen resolutions get better and my eyes get worse, but I vastly prefer crisp fonts for screen use.
When I switched from Windows 2000 to Ubuntu 6, I spent hours tweaking fonts.conf in the hope of getting something that looked as good as the standard Windows fonts, without much success. It's gotten easier now.
I wish these perennial programming font lists would make clear up-front which fonts are designed with anti-aliasing (or ClearType) in mind.
I don't like the fuzzy look of anti-aliased fonts, plus I typically work with two monitors, one in landscape mode, and one rotated 90 degrees for portrait mode. I don't think ClearType works correctly in this case anyhow.
So far I haven't found anything I like better than BitStream Vera Sans Mono.
When I switched from Windows 2000 to Ubuntu 6, I spent hours tweaking fonts.conf in the hope of getting something that looked as good as the standard Windows fonts, without much success. It's gotten easier now.