Of the Fab Five it's Roy > Donna >= Wally > Dick > Garth for getting fucked over. Garth had the least amount of fucking over available to him since he was rarely in a comic, so that's a bit skewed. During Didio's tenure Dick has, amusingly, had a lot of great things come his way. Grayson, Batman and Robin, Court of Owls, Black Mirror, etc etc. Ric is really his biggest failure under Didio's tenure and that's, as awful as it is, only been a handful of months of awfulness. He never erased Dick from history or cancelled his comic.
Donna and Wally is a tossup, Wally lost more and got fucked over more only because he had more before Didio, but Donna basically got fucked over in every way she could just like Wally.
No one comes close to Roy. Fucking Cry for Justice, Rise of Arsenal, Lian, Red Hood Sidekickism, existing for Roy has been a struggle since 2005. He had like maybe 2 good years at the start in JLA where he was Red Arrow before it was just...awful.