I would rank the carbonoids (except Leo and Seiko due to lack of information) thusly:
1. Darwin = I like his personality, it is more grey compared to the other carbonoids who are pure villains. I also really like his ability of gene manipulation. Also, best design (my opinion).
2. Himiko = Maybe not the nicest character but we do get to see her logic behind her support of the carbonoids. I also find her ability to be really cool and I can imagine many different ways of using it.
3. Galois = He was kind of rushed and I do not have much to say about him as a character. But his ability of dimensional shifting was really cool, especially the worms (altough I did not completly understand their connection to his ability).
4. Newton = A bit of a stereotypical villain and control of gravity, while the ability to create black holes are awesome, is in my opinion not as good of an ability as the ones above.
5. Zeno = Weird looking, has a nonsensical goal and an illogical power. My least favorite.
I think that 20th century scientists are quite underrepresented and I would have liked to see characters like Einstein (power over nuclear fission), Freud (power over the mind) and Curie (power over radiation).