I don’t find that ballet flats give me enough support but I do love my Arturo Chang ones any way. My comfy flats are Enzo’s, look good with either a skirt and tights or pants with thin socks.
For attention-getting style, I go with Fluevog. Definitely quirky, collector type of shoes. Most are not flats, but some are. (I generally favor flats. Never learned to walk in heels to begin with.)
Clarks .
If you want quirky, @Motherofdragons recommended Hot Chocolate Design mary janes:
https://www.amazon.com/Hot-Chocolate-Design-Chocolaticas-Multicoloured/dp/B00LLPRBOQ
Plenty of colors and designs to pick from, and they would look cute with leggings. 
Those are cute
Sometimes Sierra has amazing deals on Frye and some other brands mentioned in this thread, especially if you find a coupon
http://www.sierratradingpost.com/womens-shoes~d~266/specdataor~style!flats/frye~b~6553/
This is an uncommon choice, but I always had good luck with Anne Klein; great prices and very comfortable.
The only flats I have must have “fluffy” heels. Cole Haan, Banana Republic the original Aerosole, some Chanel, Tori Birch,and Jimmy Choo.
Thanks!
SoftWalk Narina is the holy grail of flats.
I also have a pair of Geox flats that served me well on vacations with several hours of walking per day. They are made so well… several year and they look like new. I bought them on a discount site for under $60.
6pm has them at a great price right now (of course in limited colors and sizes). 
HIMom, if you refer to Geox, mine are still going strong 
I am kinda tired of them, but not ready to replace them… what if the design has changed and they will not fit so well!
I was referring to the Softwalk Narnia. I suspect some of the other shoes mentioned are likely available as well.