I expect most replies to be things like Masterpiece Megatron, the alternators mustang mold (grimlock/wheeljack), rotf prime, things of that sort, am hoping for some surprises though. Masterpiece Megatron, I actually wouldn't consider for this honor to be honest. I LOVE his transformation, it is IDENTICAL to his G1 self, just..more detailed, a perfect update. The only real problems come with fragility, and even then most of that comes from the overall feel of the figure or people forcing things in ways they just are not meant to be forced. RotF Prime is..a bit much, but it's when you couple him with RotF Jetfire that things get nasty. Jetfire's transformation to vehicle mode is a bit of work in and of itself with all the back panels of the jet mode being a real pain in the ass to get to align and stay in place. Combing these two though is a royal fuck you from the designers. If you're gonna make major sacrifices to a figure for a combination, make the damn combination fun to do. God I can't believe I ever split the damn thing apart after the first time I did it, but recombining him this time was just a test of my will to not throw the thing through the wall. Didn't help that I was working on 1 1/2 hands as I kinda stabbed my left earlier cutting up some meat. The parts I thought I'd have trouble with (getting the gray clips from Jetfire attached and the belt piece around Prime) were fine, it was the damn leg combination that got my blood boiling. I have no idea how many times I had to retry it just to get Prime standing fucking straight. They're combined now, and there is no fucking way I am taking that thing apart again, it's done.