Building site from scratch - SEO decision

Hi guys,
I'm building my first site which I want to make a success. I studied SEO for the past month, and I learned a ton, but I need to make a decision and I can't decide what to do. I would greatly appreciate if you could help me (or suggest sources which I can use)
I'm building a site in a certain niche which addresses "how to" questions regarding single category which contains 200+ topics. In google search, there are 6 websites which rank for each of the 200 topics in TOP10.
First half of sites (old hobby sites)

• content structure: have content addressing multiple topics at a time (out of the 200+) with super thin content (30-50 words) per topic i.e. a single page can have 700 words addressing 10 topics

• # of pages total: ~30 html pages

• pages characteristics: basic html pages that load very fast without additional javascript

• focus: single category with 200+ topics. They don't address any other category than the one that I want to address

• backlink profile: around 50 links to the homepage & very few (uf any) to subpages

Second half of sites (big sites with big budgets)

• content structure: have content per single topic with anywhere from 250-1000 words (with average being 700), but not very focused on search intent.

• # of pages: thousands

• pages characteristics: contain heavy loading pages with many HQ pictures unrelated to keywords + bloated javascript

• site focus: many other categories that I don't want to address

• backlink profile: very strong profile with 200k-500k backlinks, but most of the time there are 0 or up to 3 backlinks to subpages

Very often, the niche-focused sites from the first half outrank those with very strong backlink profile that focus on other topics. I assume that users also prefer less bloated sites and often prefer to see many topics at a time to see comparison (vs. single topic with long content)
Which content structure would you follow if you wanted to compete on search ?

• a) same as sites in the first half (but focus on link building & basic SEO)

• b) same as sites in the first half which display many topics at a time, but for every topic there should be a link to a separate page targeting only a single topic (which would mean that I would have 250+ pages in total)

• c) same as b) but instead of linking out to separate page, more content would be available to the user when he clicks a button "show more" which would reveal hidden content per single topic.

Option b) would be better because the site would load faster but option c) would be better from link building perspective cause fewer pages. I'm bit lost to which approach is better. If something is not clear please ask, I'm happy to explain more.