This is just a personal opinion.
I’d like to see the following series published in the US in English (some can be found in Japanese kanji, French, and Spanish (some are in other languages like German, Chinese, etc.)). This list is not complete:
Josei:
Princess Jellyfish Kuragehime 海月姫 by HIGASHIMURA Akiko 東村アキコ
Happy Marriage Hapi Mari はぴまりby ENJOUJI Maki 円城寺マキ
Natsuyuki Rendezvous 夏雪ランデブー by KAWACHI Haruka 河内遙
Sekine’s Love SEKINE-KUN NO KOI 関根くんの恋 by KAWACHI Haruka 河内遙
Kids on the Slope Sakamichi no Apollon 坂道のアポロン by KODAMA Yuki 小玉ユキ
Yoru Café. – My Sweet Knights ヨルカフェ。by ENJOUJI Maki 円城寺マキ
5-ji Kara 9-ji Made From Five to Nine 5時から9時まで by AIHARA Miki 相原実貴
Diamond Life ダイヤモンド・ライフ by FUJIWARA Akira 藤原晶
Light of the Firefly Hotaru no Hikari ホタルノヒカリ by HIURA Satoru ひうらさとる
BL:
World’s Greatest First Love: The Case of Onodera Ritsu Sekaiichi Hatsukoi 世界一初恋 ~小野寺律の場合~ by NAKAMURA Shungiku 中村春菊
Pure Romance Junjou Romantica 純情ロマンチカ by NAKAMURA Shungiku 中村春菊(was once partially published in the US)
Love Stage!! ラブ・ステージ!! by EIKI Eiki 影木栄貴and ZAOU Taishi 藏王大志
Back Stage!! by EIKI Eiki 影木栄貴and ZAOU Taishi 藏王大志
Mr. Kayashima’s Graceful Life Kayashimashi no Yuuga na Seikatsu 茅島氏の優雅な生活~プロポーズ編~ by TONO Haruhi 遠野春日and MAMAHARA Ellie 麻々原絵里依
Like the Beast Honto Yajuu ほんと野獣 by YAMAMOTO Kotetsuko 山本小鉄子
Another Sleepless Night Konya mo Nemurenai 今夜も眠れない by YAMAMOTO Kotetsuko 山本小鉄子
A Blessing on Your House! Omairi desu yo お参りですよ by YAMAMOTO Kotetsuko 山本小鉄子
No Money Okane ga Nai お金がないっ by SHINOZAKI Hitoyo 篠崎一夜and KOUSAKA Tohru 香坂透
Cool as you Toshishita no Ryuugi 年下の流儀 by MARUYA Kae 円屋榎英
(most titles in Asuka Ciel)
Shojo:
Anything by AKINO Matsuri 秋乃茉莉
Hakkenden – Touhou Hakken Ibun 八犬伝 東方八犬異聞 by ABE Miyuki あべ美幸and TAKIZAWA Bakin タキザワバキン
Honey Bitter ハニービター by OBANA Miho 小花美穂
Spirit Detective Yakumo Shinrei Tantei Yakumo 心霊探偵八雲 by KAMINAGA Manabu 神永学 and illustrated by ODA Suzuka 小田すずか(manga)
Akaya Akashiya Ayakashi no あかやあかしやあやかしの by HaccaWorks* and Nanao 七生
The Sleepy Residents of Birdcage Manor Torikagosou no Kyou mo Nemutai Juunintachi 鳥籠荘の今日も眠たい住人たち by KABEI Yukako 壁井ユカコand TAKARAI Rihito 宝井理人
Two Soaked in Sin Tsumi ni Nureta Futari 罪に濡れたふたり by KITAGAWA Miyuki 北川みゆき
Shonen:
Youko x Boku SS Inu x Boku SS 妖狐×僕SS by FUJIWARA Cocoa 藤原ここあ
Seinen:
Ito Junji’s Cat Diary 伊藤潤二の猫日記よん&むー by ITOU Junji 伊藤潤二
My Girl マイガール (佐原 ミズ) by SAHARA Mizu 夢花李
Piano Forrest Piano no Mori: The Perfect World of Kai ピアノの森 – The perfect world of KAI by ISSHIKI Makoto 一色まこと
Thank you Rini-chi for the use of your fan art: Demo: Hakkenden
http://browse.deviantart.com/#/art/Demo-Hakkenden-351050332?hf=1
http://rini-chi.deviantart.com/
Thank you Miyukiko for the use of your fan art: Inu x Boku SS
http://browse.deviantart.com/#/art/Inu-x-Boku-SS-311260514?hf=1
http://miyukiko.deviantart.com/
Thank you piratekit for the use of your fan art: Desktop
http://piratekit.deviantart.com/art/Desktop-139022950
http://piratekit.deviantart.com/
Thank you Seunghana for the use of your fan art: Sekaiichi hatsukoi Yukina kou Kisa Shouta ~VI
http://seunghana.deviantart.com/art/Sekaiichi-hatsukoi-Yukina-kou-Kisa-Shouta-VI-322154978
http://seunghana.deviantart.com/
Thank you fuwishi for the use of your fan/cosplay art:Rendezvous
http://fuwishi.deviantart.com/art/Rendezvous-335881630
http://fuwishi.deviantart.com/
Thank you 0214 for the use of your fan art: Sakamichi
http://0214.deviantart.com/art/Sakamichi-320892215
http://0214.deviantart.com/
Thank you Jeneko for the use of your fan art:Natsuyuki Rendezvous!
http://jeneko.deviantart.com/art/Natsuyuki-Rendezvous-323904031
http://jeneko.deviantart.com/
Thank you Ultimate-Low for the use of your fan art: Sekaiichi Hatsukoi manga coloring
http://ultimate-low.deviantart.com/art/Sekaiichi-Hatsukoi-manga-coloring-284608528
http://ultimate-low.deviantart.com/