I've been pretty obsessed with the genre lately and have a bunch that I'm reading atm, but I'd love to read more! Things like The Duchess' 50 Tea Recipes, Here Comes the Silver Spoon!, etc.

Bring the Love
Remarried Empress
Crimson Karma
Kill the Villainess
Lady Evony
I'm the Stepmother, but My Daughter Is Too Cute
The Knight and Her Emperor
The Lady and the Beast (Hongseul)
Untouchable Lady
They Only Remembered Her
Roxana
Miss Not-So Sidekick
Beware the Villainess!
The Villainess Turns the Hourglass

~4400 manga completed
~1700 ongoing...

the ones that Aremon mentioned are all great, I especially recommend miss not so sidekick.
here are some more that i have loved

The Reason Why Raeliana Ended up at the Duke's Mansion is my all time favorite! seriously read it!!
Who Made Me a Princess is also super good
The Fantasie of a Stepmother
For Better or for Worse
I Became the Wife of the Male Lead
Villain Duke's Precious One
The Remarried Empress
The Falcon Princess
Elixir of the Sun

not many chapters of these ones out but they look like they are going to be good
This Time I'll Live as I Wish
I Raised a Black Dragon
The Bad Ending of an Otome
Another Typical Fantasy Romance

and then if you dont mind a tragedy I have really enjoyed this one so far, but its gonna be a sad one for sure
The Time of the Terminally Ill Extra

also anything done by Bored Corona Kids is usually pretty good.

anyway these are my favorites but I can suggest more if you want me to, I have been pretty obsessed with this type of story lately lol

[img]http://24.media.tumblr.com/3b280fafb72cad0f718be64368e64ca7/tumblr_myylzmuiY41rw3pzao4_250.gif[/img]
Like educational manga? take a look at Ed U. Manga's list of manga here