The Brainstorm toy is a good "play" toy compared to the other Voyagers of the line (Springer, Sandstorm, Blitzwing for instance are all much more complicated) and a very poseable robot. One note though is that the head can be hard to remove (which is needed to transform it).

The Nightbeat toy can be a bit tricky to get back into car mode, requires several bits to line up carefully. Something like Trailcutter might be a better option for a car robot. Orion Pax is also a pretty well loved toy (and he's kind of Optimus Prime ) The Armada Starscream toy would be a good fun toy too for the kids, and a good foe for the Windblade toy.