I think with this site, you do see a lot of variety and one person could read like 20 or 30 previously “unknown” books or series rate and review them, and give them some exposure to the Japanese learning community.
I really haven’t been active in the online Japanese learning community for a while, but my experience was that it seemed like everyone recommended the same things. “Well, here are your three options… there is literally nothing else…”
If you want recommendations for 4-koma manga that are popular in Japan but unheard of in the Japanese learning community, I got you covered!
You are totally right that the same things get recommended over and over. 
I guess we only help change that by reading and grading more books. Hopefully, people will feel confident enough to read books outside the “three options” if they see other works placed at a similar level.
One of the big places that built my current backlog is specifically the 相性 page in Bookmeter - 相性 - 読書メーター (bookmeter.com). Once you submit a decent number of books/manga in there you can get some people with really similar taste showing up in your list. I love browsing the reading lists of some of the people I’m top matched with.
I’d like to try this but so far I haven’t got any matches on the 相性 page 
I’ve put in ten books: do you remember roughly how many you had before you got matches?
No sorry, I don’t remember exactly but I think I had it from the start. Put in 15-20 the day I made the account so hopefully you’re not too far off!
Additionally, I think 読みたい本 also affects it, so you could hasten the process by adding a few books you are curious about.
Thanks for the advice! 
Aha that’s a good idea, thanks!
So anime is a tool for promoting book sales and basically that’s how I find stuff I like. Recently I have been on a huge reading kick and its hard for me to find stuff that is popular and doesn’t have an adaptation because often its a series’ popularity that leads it to get adapted.
As a result I have been perusing the book store and just seeing what looks cool. I try to keep in mind the books I haven’t read yet, but that’s my current trend. Right now I am reading 青ブタ８ and thats the first in the series that doesn’t have a anime adaptation. Next I am probably gonna read スパイ教室 since it doesn’t have an adaptation (yet, 2023).
i’ve mostly been going “ooh, there’s a manga to this (relatively obscure) anime i liked? i’ll try reading that” 
or also, someone mentions a manga related to something i liked, so i decide to try it out.
so it’s partly just following my own interests, partly more or less random “that looks kind of cool” moments. and so far it’s mostly been pretty good choices
Most of the manga I have are based on games (Legend of Zelda, Tales of Vesperia), anime (Naruto, Demon Slayer) or obscure manga most people have never heard of that I found by chance years ago (Dragon’s eye).
I tend to look at reviews or blurbs or such when trying to pick out new ones that I’ve liked the look of the cover on or liked the idea of the story from the short blurb I’ve read or the review. I also tend to search for keywords if I’m struggling to pick stuff out and then narrow down the options by reading the blurbs and reviews to see if I may be interested in the story.
