Past studies suggested slight differences:

- serif was claimed to lead to better horizontal tracking... so better for long prose readability

- sans serif was claimed to lead to better spot-recognition of characters... so better for spot-character/word recognition and legibility

Those effects were never very strong, and varied depending on the exact fonts in use (and for digital, font rendering characteristics).

There's also probably an effect based on what you're used to. If most of the books you read are serif (which they would be for older people, since almost all printed books were serif), and your exposure to sans serif was largely via the internet, and you don't like most of what's written on the internet, that might sway you toward serif. Conversely, if you mostly read modern internet text, you might have the opposite bias.