Pricing/billing strategy, monthly vs. annual?

Using a freemium model, but deliberating on whether to use annual or monthly reoccurring billing for the upgrades.

In doing so, it would divide the annual limitations by 12, limiting the amount of content needed to populate the platform (which is based on community).

On the other side, is it true that monthly plans can increase user acquisition? I understand that they may, but in the case that a user values the product enough to keep upgrading each month, wouldn't they just as well enroll annually?

I see the pros and cons to both sides, what do you all think? (keeping in mind sustainability as well)

Thanks!