Hard to say, since I met a lot of both, growing up in the 80's and 90's. I vastly prefer
Jennifer, though. I just like the sound of it a lot better than
Jessica.
Jessica has "ick" in the middle, which puts me off. And, I love the NN Jen/Jenny.
"And by the way, dearie, your punctuation sucks canal water!" -The Ghost of
Vivian Vance