It's an old question, but an important one. Let's see if we can get a good, nuanced, ideally evidence-based answer. So, old-school wisdom (certainly, how I was taught back in the day) says that serif ...
All I could find on the subject was this paper, which is pretty interesting in itself. But it only deals with preference. 57% of the test subject prefers hyphenated text. This is kind of surprising ...