To me, manga published in Ribon (Shueisha) are unexpectedly great; everything looks adorable because of the drawing style, but it is precisely not. Most of times the stories are more realistic than some directed-to-older-audiences manga, and I don't find the female leads annoying at all because of the plot, or some other character justifying their behaviour. If any of you still haven't read any of them I strongly recommend you to give a try to Nanairo Kakumei and Buddy Go!. Especially the last one.
Welp, topic. Just curiousity. Let's see how many Ribon lovers we have 😀

Ribon is about as boring as girl´s manga magazine gets. There are no huge drops but almost no highlights either. Certainly no realism. Cookie is what i call a good magazine, somehow teen targeted too. Now to answer the questions, after having a quick look at wiki: Probably Full Moon o Sagashite, the author´s one good manga.

I also read EU/US comics and am a librarian.
Manga-Masters, My ANN-Lists + Imdb

Well, when I read shoujo I mostly do it searching refreshing romance, and so I still Ribon characters are the most rational and lovable ones for what I'm looking for :B Inside flowery shoujo I find almost every manga from Ribon untypical and dragging, despite being dedicated to a way younger audience than I am - maybe my taste is childish, can't help it. A different opinion is not unwelcome though
From Cookie I've only read Six Half, whose plot I found dragging because it wasn't the main thing. I started it thinking it would be a normal josei. Oh, how wrong I was.
I see, Tanemura Arina... I read Neko to Watashi no Kinyoubi but didn't like it that much. I'll read it anyways! Thank you!

I don't usually pay attention at the magazine that publishes the series, but since you asked about a specific magazine I went to see if I had read anything published in Ribon.
It looks like I've only read 2 series from Ribbon
Aishiteruze Baby & Atashi wa Bambi

I can't say which I enjoyed more since its been a while, but I think I liked Atashi wa Bambi more.

Yeah, for the combination of adorable art and good unexpected story, Ribon is one of the best. Many Ciao's story are too childish and Nakayoshi's are so easy to expect.

I also like how Ribon manga male lead are not the usual price charming that many shoujo have. Nanairo Kakumei has "doesn't give a damn" male lead, Buddy go has him as rival, Nekota is a cat faced boy, Honey lemon soda has cold-pull and push weirdo, Kimi dake's male lead is kinda stupid and childish, etc.

best art: Nanairo Kakumei, Kirameki Lion, Hakoniwa monster, Kimi dake
Best character: romantica clock, Nekota, buddy go, Nanairo Kakumei,
Best storyline: romantica clock, nanairo kakumei, Nekota.

I don't even wonder why Nanairo Kakumei is the top manga in ribon for three years straight, lol.

Gonna read Aishiteruze Baby, Atashi wa Bambi, Hakoniwa Monster, Kirameki no Lion Boy and Romantica Clock, as I've already read/I'm reading the other ones.
Thanks everyone! 😉