Honestly I've never minded any of the
concepts. Executions, though...
The Energon Autobot multiforce combinations were the awesomest idea ever to be done overall poorly.
A few really did it well, but a lot of the time it felt like the toys were trying too hard to be too many things at once on too small a budget. A real shame, because the
concept of the Spark of Combination totally engages the Brave fan in me.