I'd have to say the CDTV, as it was not much more than an A500 in a desktop with an integrated CD-ROM. Most of what it can do can be done by expanding an A500.
I think the Fat Agnus - display controller that it came with should have at least been an AGA. Perhaps throwing an A1200 in the same box would have made the CDTV a better hit.
Certainly an interesting machine, but I think it was released a little late (1991).
