Starscream always has been my favorite charector by far. He's what a good villain should be. He's dangerious and unpredictable, and is out for his own best interests. At the same time there's an air of tragedy around him. Like all great villains you tend to sympathise with him. He's taken for granted, his boss is overbearing and abusive and never listens to him even when he's right, and he's had a friend turn his back on him.
Armada Starscream was a breath of fresh air. I was worried they'd try to pidgeon hole him into being a watered down rehash of G1. I was both surprised and delighted that they decided to go the inverse with him. Making him an honorable warrior should have made me mad. But it didn't. It fit, and I loved that he stood up for what he believed in and what he saw was right. When he sacrificed himself to prove a point and unite the Autobots and Decepticons against Unicron was touching and at the same time a sucker punch to me.
Cybertron (I'm skipping Energon/Super Link as that wasn't really Starscream, but an entirely different charector.) The most awesome version of Starscream since G1. He was a powerhouse, a juggernaught of unstoppable fury. Not one to sit back and plot he took his destiny by force. C-Starscream had numerious victories over C-Megatron and held his own against C-Optimus. But the greatest moment was when he took on the God/Creator of the Transformers: Primus. He lost both times but that wasn't the point. The point was outside of Unicron no other mech had the bearings to do what he did.
Now a present for all the fangirls (I'm not one. I'm a dude. And a Studicon at that.

). I went looking on the 'tube for some tribute videos and found 3 for each of the charectors listed. All bad ass.
http://youtube.com/watch?v=l5xdDvhUdgkhttp://youtube.com/watch?v=6dNsSm-AUH8 Don't like Linkin Park at all. But the song fits for some reason.
http://youtube.com/watch?v=7yL0ENPiFsA Made by our very own Meverix