I definitely remember Flopsy, Mopsy, Cottontail, and Peter Rabbit from my childhood but I unfortunately was never introduced to the other delightful characters of Beatrix Potter (that I remember anyway!)
These stories were adorable and I loved how all the characters interacted in other stories.
I think my favorite would have to be Mrs. Tiggy-winkle if only because of this description of her:
"Her print gown was tucked up and she was wearing a large apron over her striped petticoat. Her little black nose went sniffle, sniffle, snuffle, and her eyes went twinkle, twinkle, twinkle; and underneath her cap-where Lucie had yellow curls-that little person had PRICKLES!"
Tucker stayed true to Peter Rabbit-I guess he continues to appeal to children for a reason! He loved the how he was chased by Mr. Mcgregor and outsmarted him!