It’s important to approach a niche from a structural point of view, rather than a competition point of view. Ie, build pages based on the niche its self, not the competition level of the keywords.
There’s page strength, page relevance, authority(Site wide metric), topical relevance(site wide metric). Some people talk about ‘trust’ too, but I consider trust as being part of authority. I think those 4 metrics are ideal for analysing sites.
I advise building sites with at least 20-30 articles so you have enough topical relvance, and when you do that you’ll be creating pages for enough keywords that you’ll target some lower comp and some higher comp anyway.
But what you’re looking for is a niche, that overall, averages around a competition level you’re happy with. Building 1-2 page sites isn’t going to get you much success, you should be building sites with 20-50 pages, and for that you need an entire niche.
SEO is no longer a “keyword game”. We don’t target and not target individual keywords. You find a general niche that looks, overall, on average to be at a competition level you feel you can compete with. You then dive deep into all the keywords for that niche and group them together, just so you can really feel the niche out and put together content ideas for groups of keywords. You aren’t actually working at the individual keyword level and deciding “Ok, this has buyer intent, this doesn’t, so I’ll exclude this”, and “This doesn’t have enough volume, so I’m excluding this”.
Exclude NOTHING. Be as inclusive as possible.
What tool are you using for your silo diagrams?