Who did Jane Austen describe as “the finest comic writer of the present age?” The answer is: her older sister Cassandra.
My dearest Cassandra,
The letter which I have this moment received from you has diverted me beyond moderation. I could die of laughter at it, as they used to say at school. You are indeed the finest comic writer of the present age.
Alas, while Cassandra preserved many of Jane’s letters to her (such as the one quoted above), few of Cassandra’s own writings survive. Two of her letters to a niece remain, although as they were written very shortly after Jane’s death, they are hardly what you would call comic.