Serif fonts read fine on any screen with at least a pixel density of Apple's Retina displays. Subjective preferences are another matter, of course. I prefer serifs even on worse displays, because my brain decodes them better. And I will basically refuse to read sans serif in print, or rather, my brain refuses to comply anyway.
Some of the most beautiful and enjoyable fonts I have used in my 300-dpi e-book reader have serifs.
- Ancizar
- Bookerly
- Imperial (the one used by NYTimes)
- Palatino