#5 Ratchet
Perhaps this was the most exclusive of the figures to get of the entire Siege line. Him being able to transform into the medical bay plus him having a wrench/gun (repair) gave him the versatility of fighter and doctor. Despite being a remold of Siege Iron-hide, the mold worked best on Ratchet and a nice update to his G1 look.
#4 Refraktor
One of the most versatile figure of all the Decepticons. Then again, I wouldn't be too sure since I haven't opened up Brunt yet. But lots of replay value and very customizable. This guy was so amazing that Hastak decided to release a G1 toy colored version of him (the trio) and it came with more accessories giving him more of a definable camera look.
#3 Ultra Magnus and Jetfire
This guy was a two in one. City Commander at its finest.
#2 Shockwave
Now this guy is the epitome of Decepticon awesome-ness! One of the first Decepticon figures to be launched in this line and he came with array of customizations thanks to his armor. Use your imagination!
#1 Omega Supreme
Total G1 awesomeness! The bigger the better and there is no bigger words to express how great this figure came out to be. This figure really makes you feel like a child again but with so many bells and whistles!
Final words: Maybe this isn't the most comprehensive list constructed; I have yet to open Sixgun, Chromia, Mirage, Impactor, Brunt and Springer as I made this list. Maybe I will update this list down the line when I finally open them all. I am probably going to get AstroTrain, Lancer and the Refraktor 3 pack somewhere down the road. But I personally feel that this list is good as it gets. Take care folks.