I have written the above posting before reading the complete research paper linked by the previous poster.
After reading the complete paper, I have seen that the study is much worse than I had supposed based on its abstract.
This study is typical for the font legibility studies made by people without knowledge about typography. I find annoying that such studies are very frequent. Whoever wants to make such a study should consult some specialist before doing another useless study.
The authors claim that a positive feature of their study is the great diversity of fonts that they have tested: 16 fonts.
This claim is very false. All their fonts are just very minor variations derived from 4 or 5 basic types and even those basic types have only few relevant differences from Times New Roman and Arial.
All their fonts do not include any valuable innovation in typeface design made after WWII, and most fonts do not include any valuable innovation made after WWI. They include a geometric sans serif, which is a kind of typeface created after WWI, but this kind of typefaces is intended for packaging and advertising, not for bulk text, so its inclusion has little importance for a legibility test.
I would classify all their 16 typefaces as "typefaces that suck badly" from the PoV of legibility and I would never use any of them in my documents.
Obviously, other people may not agree with my opinion, but they should be first exposed to more varied kinds of typefaces, before forming an opinion about what they prefer, and not only to the low-diversity typefaces bundled with Windows.
After WWII, even if the (bad in my opinion) sans-serif typefaces similar to Helvetica/Arial have remained the most widespread, which have too simplified letter shapes, so that many letters are ambiguous, there have appeared also other kinds of sans-serif typefaces, which combine some of the features of older sans-serif typefaces with some of the features of serif typefaces.
In my opinion, such hybrid typefaces (e.g. Palatino Sans, Optima Nova, FF Meta, TheSans, Trajan Sans) are better than both the classic serif typefaces and the classic sans-serif typefaces.