Risa

I don't think that any character got shittier writing than her, with the exception of maybe Yar's death, and even then I think you still have to give it to Troi because she's got many more episodes. But her episodes are the ones that are the most consistently bad. Data's are mostly great, Worf's also pretty solid, Geordi has some stinkers mostly because the only thing they could figure out to do with him is have him lust after an unavailable woman, Crusher only has a few that are hers and honorable mention for one of my bottom five TNG eps of all time, Sub Rosa, but Troi's are pretty much all stinkers. The only one that I can think of off of the top of my head that I like is the one where she decides to take the command test.