Hellloooooo

i prefer these without harem too! ill start creating a list,, itll take around 3 minutes though!

http://www.mangago.zone/read-manga/one_piece/ (my favorite shounen of all time and longest shounen ive ever read. hard to catch up at first, but once you do, youll return every day to see if it updates)
http://www.mangago.zone/read-manga/onepunch_man/ (super popular im sure youve read it but just in case here it is!)
http://www.mangago.zone/read-manga/lv999_no_murabito/ (op mc and cute female lead!)
http://www.mangago.zone/read-manga/innocent_devil/ (badass female mc and amazing fights)
http://www.mangago.zone/read-manga/kakegurui/ (op in gambling but not physically)
http://www.mangago.zone/read-manga/tomodachi_game/ (personal shounen fav, insane mc and rival characters! game concept where everybody has a huge debt)
http://www.mangago.zone/read-manga/rikudou/ (fighting manga, really well done and the art is great!)
http://www.mangago.zone/read-manga/aku_no_kyouten/ (super twisted and the mc is psychotic. warning for some gorey scenes and underage sex)
http://www.mangago.zone/read-manga/beastars/ (this story is AMAZINGG! really, while the anthropomorphic animals might set you off, its super cool. the mc is cute and badass at the same time)
http://www.mangago.zone/read-manga/mob_psycho_100/ (same creator for OPM but about espers. mc is amazing and reigen is so cool)
http://www.mangago.zone/read-manga/mairimashita_iruma_kun/ (mc is brought into another world after being sold by his parents to a powerful demon! love the demon and the mc)
http://www.mangago.zone/read-manga/tensei_shitara_slime_datta_ken/ (reborn into another world as a slime who is OP)
http://www.mangago.zone/read-manga/gokushufudou_the_way_of_the_house_husband/ (not really shounen but super funny with a mc whos strong ex yakuza now house husband)
http://www.mangago.zone/read-manga/black_joke/ (no ones really OP besides my favorite gorilla man, but super cool and funny. lots of ecchi and gore)
http://www.mangago.zone/read-manga/while_killing_slimes_for_300_years_i_became_the_max_level_unknowingly/ (cute shounen manga about a woman reincarnated as an ordinary witch who got OP after killing slimes for a long time)
http://www.mangago.zone/read-manga/tensei_shitara_ken_deshita/ (man who gets reborn (i think) into a strong sword basically gets adopted by an orphan neko who has strong magic powers)
http://www.mangago.zone/read-manga/nanatsu_no_taizai/ (one of my top favorite shounen manga. love the concept, story, characters and writing. check it out if you have the time!)
http://www.mangago.zone/read-manga/solo_leveling/ (mc turns from weakest hunter to strongest in the most satisfying way)
http://www.mangago.zone/read-manga/hero_i_quit_a_long_time_ago/ (ex strongest hero gets sucked back into being a hero after a long time)
http://www.mangago.zone/read-manga/out_makoto_mizuta/ (mc isnt op but an insane delinquent fighter, really love this story)
http://www.mangago.zone/read-manga/boss_in_school/ (mcs mom doesnt want him to fight so he listens, but his dad dies and now hes the boss of i believe is some mafia type stuff)
http://www.mangago.zone/read-manga/renjou_desperado/ (badass lady looking for a husband travels around saving towns and finding men just to find that theyre all shit or taken. funny as hell)
http://www.mangago.zone/read-manga/tokyo_revengers/ (man gets sent back in time after his first and only girlfriend gets killed by a gang dispute, takes it upon himself to save them)
http://www.mangago.zone/read-manga/tensei_kenja_no_isekai_raifu_daini_no_shokugyo_wo_ete_sekai_saikyou_ni_narimashita/ (man reborn into another world as a monster tamer who tames hella slimes)
http://www.mangago.zone/read-manga/act_age/ (not shounen, but the mc is like an op actress)
http://www.mangago.zone/read-manga/maou_no_ore_ga_dorei_elf_wo_yome_ni_shitanda_ga_dou_medereba_ii/ (great black magic mage buys a strong elf slave and its cute)
http://www.mangago.zone/read-manga/kamitachi_ni_hirowareta_otoko/ (mc died in his sleep and was reborn with the purpose to live a fulfilling life as a child. super cute)
http://www.mangago.zone/read-manga/arte/ (the premise is very cool and the mc is a badass woman who was born in an era that discriminated against women. tries to become an artist anyways)
http://www.mangago.zone/read-manga/tate_no_yuusha_no_nariagari/ (one of my favs as well. the characters made me FUME but the way the mc overcomes everyone shitting on him is what makes me keep reading)
I get that halfway through i got a litttle ''cool to cute" ish but i hope you check some of these out!!(๑•ㅂ•)و✧

The grandmaster of demonic cultivation would be perfect

Woah thank u soooo much for that very detailed recommendations. It makes it easier for me to narrow down what I'll start on reading first.
(இ﹏இ｡)

P.S You're really amazing for writing this in 3 minutes. Bless your kind soul

Yassss!!! I already read up to the current translated chapter on exiled rebels and I also watched the animation and it's goddamn good!! Definitely one of the best in my BL favorites list

Thank u though (ฅ>ω<ฅ)♡