I have more but my main favs are
https://www.mangago.me/read-manga/omniscient_reader_s_viewpoint/ (just love kim dokja)
https://www.mangago.me/read-manga/return_of_the_flowery_mountain_sect/
https://www.mangago.me/read-manga/yuukoku_no_moriarty/
https://www.mangago.me/read-manga/heaven_official_s_blessing/ (xie lian is honestly more of a badass in the novel)
+1 vote for Return of the Flowery Mountain Sect MC Chung Myung and ORV MC Kim Dokja.
https://www.mangago.me/read-manga/the_dark_magician_transmigrates_after_66666_years/
Jamie is so cool but such a tsundere when it comes to receiving his families love lol. Also great because although he's reincarnated with the mind of an adult, he ain't no pedo in a child's body like many of the other webtoons.
https://www.mangago.me/read-manga/the_return_of_the_crazy_demon/
MC is unhinged and legit just crazy lmao
https://www.mangago.me/read-manga/sword_fanatic_wanders_through_the_night/
MC is ruthless, merciless and unhinged kind of like the MC for Crazy Demon but without the crazy.
i third kim dokja from orv... Nobody else comes close to my king in my eyes ..
Drop your fave strongest + badass MC here fellas (๑•ㅂ•)و✧