Should it be based on the audience, the type of content, or just personal preference?

I've been experimenting with mockups for publishing, and they really help visualize the final design before printing or going live. However, I’m still unsure about the best way to choose the right mockup for a specific project. Should it be based on the audience, the type of content, or just personal preference? Also, are there any resources that provide high-quality, professional mockups that don’t look generic or overused? Would love to hear your recommendations!