IMPORTANT NOTE: CHECK EDITOR GUIDELINES TO SEE WHO IS OPEN TO UNSOLICITED MANUSCRIPTS. GO BY SUBMISSION GUIDELINES, ONLY.
Mary Kate Castellani (Senior Editor at Bloomsbury; Facebook: www.facebook.com/marykate.castellani; Twitter: @MKCastellani) wants character-driven middle-grade. She'd "love to see a character just starting to find his or her way in the world, regardless of genre."
In picture books, she'd "love quirky, funny, wholly unique picture books. Ones that leave lots of room for illustrations."
Danielle M. Smith (Literary agent,http://forewordliterary.com/foreword/danielle-smith/) seeks author/illustrators w/unique PBs and/or MGs. Illustrators she loves: Jon Klassen, Allison Jay, Marla Frazer, Molly Idle, and Sophie Blackall. Also "MG novels that make me sob...or have me laughing hysterically" for hours/days with strong voice and characters.
Michelle Witte (http://michellewittebooks.com/; Twitter: @michellewitte) wants children's narrative nonfiction, and magical realism in MG. She is currently re-open to slush.
Roseanne Wells (http://www.jdlit.com/; Twitter: @RivetingRosie) wants MG with driving characters/voice. Also smart girls doing unexpected things.
Kristin Daly Rens (Editor: PBs&MG at Balzer + Bray; Twitter: @Kristin_rens) wants epic fantasy MG.
Rena Bunder Rosser (Literary/Foreign Rights Agent at Deborah Harris Agency; Twitter: @skyhorsepub) wants magical realism in the Middle East with "deserts and shuks...camels", etc. MG
Disclosure: the "wants" were taken from a public Tumbler feed. Requests for materials other than PBs/MG were excluded. Links came from my own online research.