For me it's really a tie between Combiner Wars and Titans Return.Combiner Wars got the Generations line back in stores after we skipped most of the thrilling thirty figures, and the main gimmick was a strong one. Some of the figures were a little "simpler" than previous offerings, but at least they were larger than the previous waves. Titans Return again featured a strong gimmick and integration between different sized figures, and boasted a wide range of less well known characters. Both lines shoe horned in characters who had never originally featured the gimmicks on offer, but at least it meant we got some of those figures.

Prime Wars has been a bit of a let down. It's doesn't really have a unique line wide gimmick of it's own. The Prime Masters are just a different type of headmaster, and the combiners are, well, combiners. The Evolution figures have been interesting, but are limited to the Leader class and not without issues of their own. It would have been great to see greater integration between the leader class and the smaller figures. It again features toys who have been shoe horned into becoming combiners. Even so, it's still great to see Transformers on the shelves in mainstream retail stores.