Trial vs Freemium

Hey guys, I run a subscription-based music learning website and we currently operate on a freemium model whereby free users get unlimited access to a small amount of pre-selected content, and can unlock the rest of the content by becoming a paid subscriber.

Which model do you personally prefer for a subscription model website with digital content:

1. Freemium (where you get access to a small amount of content forever)

2. Trial (where you get access to everything/nearly everything for a short period of time)

Are there any articles/studies/posts/reference materials you can recommend comparing the two?

Thanks in advance!