You are over thinking this.
Search engines use semantics more for weighting these days. While the old parser models still make sense, semantics plays a much larger role. Here are some answers that will provide some background before I answer your question more directly.
This answer explains how content is weighted: Why would a website with keyword stuffing rank higher than one without in google search results? Ignore the title.
This answer explains the headline read order: SEO on Single Page Website and Content keywords This is a partial explanation of the parser model and weight. Again, ignore the title.
This answer explains how terms are weighted in read order from left to right: Well structured URLs vs. URLs optimized for SEO This will help you imagine importance.
In your case, you are asking what weighs more, headers or lists, and which is more important. The most important thing to remember is to make the web page for humans and not machines. I cannot overemphasize this. Organize your content that makes sense for presentation, reading, and capturing your users attention.
Beyond that, header tags remain the most important content for weighting. These follow in order of scale such as any
h1 tag being more important than any
h2 tag which is more important than any
h3 tag. However, several
h3 tags can out weigh the
h1 tag providing that there is similarity in topic between the
h3 tags. Order from top to bottom is important too. You have to think in terms of content blocks. You should have only one
h1 tag in the beginning of your content. Any header tag should indicate the pages sub-topics in order or importance from top to bottom. Think in terms of an outline for this. Each bit of content between header tags are linked to the header tag that precedes it. As you work your way down the page, you signal importance using header tags by scale and placement as well as content from top to bottom. Each block of content gets it's importance from the previous header tag and relative placement from both the beginning of content and the previous header tag. For example, the 5th paragraph of content from the beginning of the content is more important than the 6th paragraph. As well, the 2nd paragraph following an
h2 tag is less important that the 1st paragraph following the
h2 tag. If you work using the outline mode of your word processor, you will quickly see how this works.
Ordered and unordered lists are one of the few blocks of content that is treated differently. Search engines like lists. The reason for this is simple. In the past, lists indicated important topic clues. Lists are weighted slightly higher than ordinary content but not more than the header tags. This means that a list that follows a paragraph can weigh more than the paragraph but only slightly.
For weight and topic clues, header tags are always more important than content of any kind. However, for content, lists are more important. I like to use lists often, however, do not over do it.
It is important to create your page for the user and not to over think the whole SEO thing. Pay attention to placement of topics and how you signal your topics importance using header tags thinking about how you outline your work. Organize your work in order of importance and write naturally. What is most important these days is natural content. Semantics will fully understand the page and trying to weigh too much for keywords can undo how the page really should perform in search. Focusing on keywords and sending too many signals often means a higher bounce rate. This is because keywords imagined often do not align with reality. It is very common that semantic signals in an article do not match what the author considers to be important keywords. The best advice is to write naturally with conversational titles and header tags and make small adjustments geared toward compelling content rather than specific keywords.