You can start by looking on fanfiction websites like Archive of Our Own (AO3). It has a large collection of BTS x reader fanfictions. You can use the search bar and type in 'BTS x reader' and then sort the results by popularity or rating to find the best ones.
Another way is to join BTS fan groups on social media platforms such as Facebook or Reddit. Members in these groups often share and recommend their favorite 'BTS x reader fanfiction'. They might even have dedicated threads for discussing the best ones. You can ask for suggestions in these groups and get some great leads.
Chapter 121, "Everything is Ready, Begin Taking Action [3 in 1]", is the clearest early answer because it turns Blacksmith Room's situation into a concrete plot event. Early on, Upon learning that Xia Hong wanted to make arrows, Mu Dong.... By the end, When the new houses started, there were 140 in the Logging Realm.. Inside the broader trade and resources storyline, the chapter closes with "If time allowed, I'd also like to make more bows, but it's not feasible now.
Chapter 205, "Director Emerges from Seclusion, Treasure Presentation Opportunity", is the clearest early answer because Cold Beasts gets a payoff that changes the stakes. A useful checkpoint is the way the scene starts with Speaking of which, the flying type Cold Beast, none of the people... and follows through with Arrow shower, this is a real arrow shower......" "How many....
Chapter 111, "A Turn of Fate [Triple-length Chapter]", is the clearest early answer because it turns Redwood Ridge's situation into a concrete plot event. It opens with Even daring to make a small hole to peek, he didn't dare. and closes on Hold them back, the rest, keep running, quick!" Chen Ying didn't....
Chapter 123, "Arrow Bamboo Forest, Rat King, New Camp", is the clearest early answer because the buildup finally cashes out in a real clash. The chapter gives readers a real answer by opening on Seeing the actions of the four, a trace of emotion flashed in Xia... and ending on There was no suspense, the tree's surface was pierced by the Yi....
Chapter 135, "The Fearless Mirror Immortal [Three in One]", is the clearest early answer because it turns Redwood Ridge's situation into a concrete plot event. The chapter gives readers a real answer by opening on To the north, the Cloud Mist Zone should be the territory of the Teng... and ending on The expressions on the others, though silent, made it clear they too....
Chapter 183, "Population Explosion, Valley Planning", is the clearest early answer because it turns Cheng Feng's situation into a concrete plot event. The setup is The wooden building only had 740 rooms in total, which means, on..., but the pressure keeps building through Housing has become a problem again!.
Chapter 76, "Everyone Can Cultivate", is the clearest early answer because it turns Cold Beasts's situation into a concrete plot event. The setup is Brother, what do you think of my proposal?" Xia Hong, who was..., but the pressure keeps building through He decided not to speculate further and made a rough calculation in....
Chapter 184, "Leap in Productivity, Territorial Expansion, Xia Chuan's Opportunity", is the clearest early answer because it turns Shi Ping's situation into a concrete plot event. The setup is It's imperative to let everyone know that Xia Hong's intention is..., but the pressure keeps building through Indeed, these nine things would greatly help the camp, and if more....
Chapter 106, "Expand the Hunting Grounds, Camp Expansion [3-in-1]", is the clearest early answer because it turns Zhao Hu's situation into a concrete plot event. It opens with With weapons in the Logging Realm, at most you gain some self-defense... and closes on Among the three Zhao brothers, Zhao Hu had the most impulsive....
Chapter 118, "Poison Sac, Bow Making [2 in 1]", is the clearest early answer because it turns Xia Hong's situation into a concrete plot event. The setup is Seeing the bows and arrows for the first time, the five of them were..., but the pressure keeps building through But then, after pondering for a moment, their eyes immediately lit up..