Roughest ride/dealt the worst is a kind of open to interpretation. If it's according to what they "deserve", then Theon and Cersei are straight out.
If it's what would I personally never want to have happen to me, Theon wins.
If it's injustices (not deserved), I'd say it's more of a four-way tie for second place among Jon, Dany, Sansa, and Arya, in that order.
But they all made choices, even if ignorantly. Jon chose to join the Night's Watch and break the tradition, Dany chose to pursue power and the Seven Kingdoms, Sansa chose to leave Winterfell and marry a king, Arya chose to make her list.
Jaime is an anomaly - I like him a lot, and feel for him, but he's made a ton of crap choices, few to none of them ignorant.
Tyrion is golden. Why is he on the list?
And then there's Bran. He never did anything except climb a wall he'd climbed a million times, at the wrong time. He annoys the hell out of me, but I can't for the life of me think of a single thing he's done in selfishness or malice or greed or even ignorance. His choices were taken away from him in Season 1, Episode 1. That, and assuming a life as the three-eyed raven is a life no one would want, I voted for Bran.