Guest posts vs links in existing posts- which do you prefer?

Personally, my 1st choice is getting a link in an existing post. If someone offers to sell me a link on a site I look at the backlink profile in Semrush to see which pages have the most links/referring domains. If I find a page with a lot of backlinks that's relevant to my niche I buy a link.

Guest posts involve the extra time and expense of writing the article. Since this is a new article, when it's published it has no links and can only pass the power of the domain. I feel like I'm basically hoping and praying that the website owner is doing something to build links to their articles, but that seems unlikely.

I suppose if I write a guest post it's probably less likely to have my link removed after a period of time than if I bought a link in an existing article. I feel like this is my best reason to want guest posts so far.

I have talked to a few sites about getting a link on a specific page and had them come back and offer me a guest post instead. Most of the time I pass.

If any of you guys like guest posts better I'd love to hear your thoughts. Am I missing an opportunity here?