Trending topics are short-termed content that generates active and interest. It makes use of a concept or theme that is viral currently.

Evergreen content does not have a start or end. They will always be important, but need regular edits to be up to date. There are plenty of evergreen content. What matters most is which one is more detailed and meaningful.

Making use of both is the ideal strategy.

If you have to focus on either one type, choose trends only if you can be constant and repeatedly post new content as and when new content arises.

Evergreen content does not need to be as frequent, but when it is generated, it needs to be well-crafted.