For better definitions: Simple: It's very apparent what they transform into. You can easily visualize what their alt-mode looks like when looking at their robot mode. Not too many moving parts or pieces, so it seems less likely that a piece would jam and complicate transformation. Semi-Complicated: The middle-ground. You can guess what sort of alt mode they have, indicated by wings or treads for instance, but you have to wait until they transform to really know what they look like. Complicated: The robot and alt-mode are hard to correlate. Some elements are still consistent, like color, but the bots look their most alien or complex, which can be plus for some since they are highly advanced machines who need to hide. Affiliation Lights: There are a lot of glowing bits (like their badges), usually red or purple, which indicate the Transformers' faction. In a way, this can help bots identity each other in low-light situations so they don't shoot each other... by the same logic, it can make it hard for them to hide. Across Transformers' many continuities, there have been prevailing designs or aesthetic themes that help define the continuity. The bots of G1 had simple transformations and designs; the Transformers of the live action films are notorious for their busy looks; etc. Which aesthetic is your favorite, though? There are reasons to love or dislike each one. Personally, I have to go with semi-complicated, because I feel there's the most room for creativity here, and maybe affiliation lights. I really like the idea of glowing badges not only as a way to indicate one's alliance, but also as a way to show vital signs. Still, there's room for exploitation (messing with your colors or dimming them to get a jump on the enemy).