Heeeeeeeeyyy

ONGOING (one of my top favorites of all time; psychological, smutty etc.)
http://www.mangago.me/read-manga/yononaka_wa_bokura_ni_amai/

This is a very long series (at least 10 volumes long with different titles)
http://www.mangago.me/read-manga/rules/

ALL MANGA FROM THIS AUTHOR IS GOOD
http://www.mangago.me/read-manga/yokan/
http://www.mangago.me/read-manga/yokan_ex_noise/

Psychological
http://www.mangago.me/read-manga/nobody_knows/
http://www.mangago.me/read-manga/hua_hua_you_long/

Supernatural
http://www.mangago.me/read-manga/devil_x_devil/
http://www.mangago.me/read-manga/neo_arcadia_yami_ni_saku_niji/
http://www.mangago.me/read-manga/ihoujin_etrange/

Slice of life
http://www.mangago.me/read-manga/loved_circus/
http://www.mangago.me/read-manga/aoi_haru_kai_ito/
http://www.mangago.me/read-manga/boku_o_warui_ko_ni_shite/
http://www.mangago.me/read-manga/dreamers_high/
http://www.mangago.me/read-manga/cinderella_plot/

Sweet
http://www.mangago.me/read-manga/blt_burning_love_twin/
http://www.mangago.me/read-manga/darenimo_iwanaide/

Incest (WARNING)
http://www.mangago.me/read-manga/soukyoku_megu_iroha/
http://www.mangago.me/read-manga/ai_to_makoto_moriyo/

ALL MANGA FROM THIS AUTHOR IS GOOD
http://www.mangago.me/read-manga/ubawareru_koto_marugoto_zenbu/
http://www.mangago.me/read-manga/ai_ga_aru_kara_ii_ja_nai/
http://www.mangago.me/read-manga/suki_toiunoni_nazekashira/
http://www.mangago.me/read-manga/itsumo_anata_no_koto_bakari/

This has a series of 3 mangas (all titled with WILD)
http://www.mangago.me/read-manga/wild_fangs/

This is a pretty famous series but author has been around for a long time.
http://www.mangago.me/read-manga/i_don_t_dislike_you/

AGAIN ALL MANGA FROM THIS AUTHOR IS RECOMMENDED
http://www.mangago.me/read-manga/home_drama/
http://www.mangago.me/read-manga/prince_charming/

Idk if you'll like any of these but these are some of the mangas I believe to be underrated despite their beautiful plots.