I like states that don't have straight borders. It's a reminder of how arbitrary our politics and our divisions are. That leaves, welp, just Hawaii come to think of it.
What about South Carolina? Aside from one stretch in the Northeast, it's fairly jagged.
New Jersey's borders are, except for a short stretch between PA and the Hudson in the North, also completely non-linear. Other than that, there really seems to be no state even coming close to non-straight lines as borders. Vermont maybe, expect for the border with MA?