whats up . Well there are trade offs of course, I like working in bondo/plumbers putty because I enjoy carving into parts of it after it's cured with a large round exacto so that part of the process is fun and whats great about bondo is if it's an original and it's not going to be cast the plumbers putty will never crack no matter what and it's is super tough, which sculpey is not.
What's better about sculpey is you do not have to wear gloves all the time, and so it's more comfortable in that sense. I like both materials , the bondo is incredibly tough more like resin so I think it's more collectible than a sculpey piece which can possibly develop small cracks over time, especially if near a high traffic area and are always suffering vibrations.