While one cannot discard the possibility that Deinocheirus might be an oviraptorid, being able to closely look at Gallimimus (and its front limbs included, of course) being placed next to Deinocheirus arms (at the exhibition of Mongolian dinosaurs) I would place my bet on ornithomimidae. The shape and even proportions of Gallimimus and Deinocheirus carpalia (claws of relatively equal size) are strikingly similar. In oviraptorids the first claw is usually somewhat bigger than the rest two claws.
Therizinosaurus claws are much, much longer then those of Deinocheirus and EXACTLY SCYTHE-LIKE (shape, thickness, etc..- without handle, of course!)
Beri's Dinosaur World