Darkseid and Apokolips are sort of borrowed from the New Gods title. I like Crime Syndicate and I hope DC just reboots Crime Syndicate into the main earth. I heard there is already an owl man on the main earth from the court of owls story. I think Amazo can be as great as Ultron if done right. The mind control of Starro is also a great threat.
darkseid. braniac is really evil he just sees things through logic and computations , he is indifferent as organic life is concerned while darkseid is evil , knows it , and pretty much revels in it. despero as far as this list goes is second most evil, ultra-humanite is very evil as far as PETA is concerned